diff --git a/source/games/blood/src/barf.cpp b/source/games/blood/src/barf.cpp
index a707d315d..0dc520940 100644
--- a/source/games/blood/src/barf.cpp
+++ b/source/games/blood/src/barf.cpp
@@ -576,6 +576,7 @@ void ParseScript(int lumpnum)
                         rfs.SkipBeyondValue('\n');
                     }
                 }
+                [[fallthrough]];
             }
             case kTagResource: // really light blue..
             {
diff --git a/source/games/blood/src/blood.cpp b/source/games/blood/src/blood.cpp
index 98f0078a1..39a7c0057 100644
--- a/source/games/blood/src/blood.cpp
+++ b/source/games/blood/src/blood.cpp
@@ -314,7 +314,7 @@ void GameInterface::Ticker()
 
 		for (int i = 0; i < 8; i++)
 		{
-			team_ticker[i] = team_ticker[i] -= 4;
+			team_ticker[i] -= 4;
 			if (team_ticker[i] < 0)
 				team_ticker[i] = 0;
 		}
diff --git a/source/games/blood/src/messages.cpp b/source/games/blood/src/messages.cpp
index 42fa602ca..8718c7343 100644
--- a/source/games/blood/src/messages.cpp
+++ b/source/games/blood/src/messages.cpp
@@ -266,7 +266,7 @@ static int parseArgs(char *pzArgs, int *nArg1, int *nArg2)
 {
     if (!nArg1 || !nArg2 || strlen(pzArgs) < 3)
         return -1;
-	*nArg1 = pzArgs[0] - '0';
+    *nArg1 = pzArgs[0] - '0';
     int a1 = pzArgs[1] == ' ' ? 0 : pzArgs[1] - '0';
     *nArg2 = a1 * 10 + (pzArgs[2] - '0');
     return 2;
diff --git a/source/games/blood/src/nnexts.cpp b/source/games/blood/src/nnexts.cpp
index eff55c0ae..e782b5803 100644
--- a/source/games/blood/src/nnexts.cpp
+++ b/source/games/blood/src/nnexts.cpp
@@ -493,7 +493,7 @@ void nnExtResetGlobals()
     memset(gImpactSpritesList, 0, sizeof(gImpactSpritesList));
 
     // reset tracking conditions, if any
-    for (int i = 0; i < countof(gCondition); i++) 
+    for (size_t i = 0; i < countof(gCondition); i++) 
     {
         TRCONDITION* pCond = &gCondition[i];
         for (unsigned k = 0; k < kMaxTracedObjects; k++)
@@ -2601,7 +2601,7 @@ void usePropertiesChanger(DBloodActor* sourceactor, int objType, int objIndex, D
             // data3 = set wall hitag
             if (valueIsBetween(pXSource->data3, -1, 32767)) 
             {
-                if ((pSource->flags & kModernTypeFlag1)) pWall->hitag = pWall->hitag |= pXSource->data3;
+                if ((pSource->flags & kModernTypeFlag1)) pWall->hitag |= pXSource->data3;
                 else pWall->hitag = pXSource->data3;
             }
 
@@ -2611,7 +2611,7 @@ void usePropertiesChanger(DBloodActor* sourceactor, int objType, int objIndex, D
                 old = pWall->cstat;
 
                 // set new cstat
-                if ((pSource->flags & kModernTypeFlag1)) pWall->cstat = pWall->cstat |= pXSource->data4; // relative
+                if ((pSource->flags & kModernTypeFlag1)) pWall->cstat |= pXSource->data4; // relative
                 else pWall->cstat = pXSource->data4; // absolute
 
                 // and hanlde exceptions
@@ -5062,12 +5062,11 @@ bool aiFightMatesHaveSameTarget(DBloodActor* leaderactor, DBloodActor* targetact
 
     for (int i = bucketHead[rx]; i < bucketHead[rx + 1]; i++) 
     {
-        if (rxBucket[i].type != OBJ_SPRITE)
-            continue;
+        if (rxBucket[i].type != OBJ_SPRITE) continue;
 
-            auto mate = rxBucket[i].actor;
-            if (!mate || !mate->hasX() || mate == leaderactor || !mate->IsDudeActor())
-                continue;
+        auto mate = rxBucket[i].actor;
+        if (!mate || !mate->hasX() || mate == leaderactor || !mate->IsDudeActor())
+            continue;
 
         if (mate->GetTarget() == targetactor && allow-- <= 0)
             return true;
@@ -9059,8 +9058,8 @@ bool incDecGoalValueIsReached(DBloodActor* actor)
 {
     XSPRITE* pXSprite = &actor->x();
     if (pXSprite->data3 != pXSprite->sysData1) return false;
-    char buffer[5]; 
-    snprintf(buffer, 5, "%d", abs(pXSprite->data1)); 
+    char buffer[7]; 
+    snprintf(buffer, 7, "%d", abs(pXSprite->data1)); 
     int len = int(strlen(buffer)); 
     int rx = -1;
 
diff --git a/source/games/duke/src/actors.cpp b/source/games/duke/src/actors.cpp
index 4c293f33d..037f0d10a 100644
--- a/source/games/duke/src/actors.cpp
+++ b/source/games/duke/src/actors.cpp
@@ -5099,7 +5099,7 @@ int dodge(DDukeActor* actor)
 int furthestangle(DDukeActor *actor, int angs)
 {
 	auto s = actor->s;
-	int j, hitsect, hitwall, furthest_angle, angincs;
+	int j, hitsect, hitwall, furthest_angle = 0, angincs;
 	int hx, hy, hz, d, greatestd;
 	DDukeActor* dd;
 
diff --git a/source/games/duke/src/actors_lava.cpp b/source/games/duke/src/actors_lava.cpp
index 87cb045d4..81b713de2 100644
--- a/source/games/duke/src/actors_lava.cpp
+++ b/source/games/duke/src/actors_lava.cpp
@@ -345,6 +345,10 @@ void dojaildoor(void)
 					auto wal = &wall[j];
 					switch (jaildoordir[i])
 					{
+						default: // make case of bad parameters well defined.
+							x = wal->x;
+							y = wal->y;
+							break;
 						case 10:
 							x = wal->x;
 							y = wal->y + speed;
@@ -427,23 +431,28 @@ void moveminecart(void)
 				endwall = startwall + sectp->wallnum;
 				for (j = startwall; j < endwall; j++)
 				{
+					auto wal = &wall[j];
 					switch (minecartdir[i])
 					{
+						default: // make case of bad parameters well defined.
+							x = wal->x;
+							y = wal->y;
+							break;
 						case 10:
-							x = wall[j].x;
-							y = wall[j].y + speed;
+							x = wal->x;
+							y = wal->y + speed;
 							break;
 						case 20:
-							x = wall[j].x - speed;
-							y = wall[j].y;
+							x = wal->x - speed;
+							y = wal->y;
 							break;
 						case 30:
-							x = wall[j].x;
-							y = wall[j].y - speed;
+							x = wal->x;
+							y = wal->y - speed;
 							break;
 						case 40:
-							x = wall[j].x + speed;
-							y = wall[j].y;
+							x = wal->x + speed;
+							y = wal->y;
 							break;
 					}
 					dragpoint(j,x,y);
@@ -561,7 +570,7 @@ void thunder(void)
 {
 	struct player_struct* p;
 	int r1, r2;
-	int startwall, endwall, i, j;
+	int startwall, endwall, i = 0, j;
 	uint8_t shade;
 
 	p = &ps[screenpeek];
diff --git a/source/games/duke/src/actors_r.cpp b/source/games/duke/src/actors_r.cpp
index ae85185c4..9def10751 100644
--- a/source/games/duke/src/actors_r.cpp
+++ b/source/games/duke/src/actors_r.cpp
@@ -1572,7 +1572,7 @@ void movetransports_r(void)
 {
 	uint8_t warpdir, warpspriteto;
 	int k, p, sectlotag;
-	int ll2, ll, onfloorz;
+	int ll2 = 0, ll, onfloorz;
 	Collision coll;
 
 	 //Transporters
@@ -4104,14 +4104,13 @@ void fall_r(DDukeActor* ac, int g_p)
 
 void destroyit(DDukeActor *actor)
 {
-	int lotag, hitag;
+	int lotag = 0, hitag = 0;
 	int wi, wj;
 	int wallstart2, wallend2;
 	int sectnum;
 	int wallstart, wallend;
 	DDukeActor* spr = nullptr;
 
-	hitag = 0;
 	DukeSectIterator it1(actor->s->sectnum);
 	while (auto a2 = it1.Next())
 	{
diff --git a/source/games/duke/src/bowling.cpp b/source/games/duke/src/bowling.cpp
index ac00bd71b..21c6e8e3f 100644
--- a/source/games/duke/src/bowling.cpp
+++ b/source/games/duke/src/bowling.cpp
@@ -164,7 +164,7 @@ int checkpins(int sect)
 
 void resetpins(int sect)
 {
-	int i, tag;
+	int i, tag = 0;
 	int x, y;
 	DukeSectIterator it(sect);
 	while (auto a2 = it.Next())
diff --git a/source/games/duke/src/gameexec.cpp b/source/games/duke/src/gameexec.cpp
index 0795d46b0..05cd8cce3 100644
--- a/source/games/duke/src/gameexec.cpp
+++ b/source/games/duke/src/gameexec.cpp
@@ -2989,7 +2989,7 @@ int ParseState::parse(void)
 		lMaxDistVar = *(insptr++);
 		lVarID = *(insptr++);
 		lMaxDist = GetGameVarID(lMaxDistVar, g_ac, g_p);
-		DDukeActor* lFound;
+		DDukeActor* lFound = nullptr;
 		lDist = 32767;	// big number
 
 		DukeStatIterator it(STAT_ACTOR);
diff --git a/source/games/duke/src/player_d.cpp b/source/games/duke/src/player_d.cpp
index 98fbb5c9d..eddc14f45 100644
--- a/source/games/duke/src/player_d.cpp
+++ b/source/games/duke/src/player_d.cpp
@@ -148,7 +148,7 @@ static void shootfireball(DDukeActor *actor, int p, int sx, int sy, int sz, int
 static void shootflamethrowerflame(DDukeActor* actor, int p, int sx, int sy, int sz, int sa)
 {
 	auto s = actor->s;
-	int vel, zvel;
+	int vel, zvel = 0;
 
 	if (s->extra >= 0)
 		s->shade = -96;
diff --git a/source/games/duke/src/player_r.cpp b/source/games/duke/src/player_r.cpp
index 0472f51f9..526aeee1e 100644
--- a/source/games/duke/src/player_r.cpp
+++ b/source/games/duke/src/player_r.cpp
@@ -209,7 +209,7 @@ static void shootweapon(DDukeActor* actor, int p, int sx, int sy, int sz, int sa
 {
 	auto s = actor->s;
 	int sect = s->sectnum;
-	int zvel;
+	int zvel = 0;
 	int hitsect, hitwall;
 	int hitx, hity, hitz;
 	DDukeActor* hitsprt;
diff --git a/source/games/duke/src/premap_r.cpp b/source/games/duke/src/premap_r.cpp
index fe51152c1..961dae7eb 100644
--- a/source/games/duke/src/premap_r.cpp
+++ b/source/games/duke/src/premap_r.cpp
@@ -499,6 +499,7 @@ void prelevel_r(int g)
 		{
 			int ii;
 			int childsectnum = -1;
+			dist = 0;
 			DukeSectIterator it(i);
 			while (auto act = it.Next())
 			{
diff --git a/source/games/duke/src/spawn.cpp b/source/games/duke/src/spawn.cpp
index 324cdefba..b3aeea4e3 100644
--- a/source/games/duke/src/spawn.cpp
+++ b/source/games/duke/src/spawn.cpp
@@ -624,7 +624,7 @@ void spawneffector(DDukeActor* actor)
 	auto sectp = sp->sector();
 	int sect = sp->sectnum;
 	auto t = actor->temp_data;
-	int startwall, endwall, x, y, d, s, clostest;
+	int startwall, endwall, x, y, d, s, clostest = 0;
 
 	sp->yvel = sectp->extra;
 	sp->cstat |= 32768;
diff --git a/source/games/exhumed/src/move.cpp b/source/games/exhumed/src/move.cpp
index eb83372d0..5177de159 100644
--- a/source/games/exhumed/src/move.cpp
+++ b/source/games/exhumed/src/move.cpp
@@ -288,7 +288,7 @@ int BelowNear(DExhumedActor* pActor, int x, int y, int walldist, int nSector)
 
         if (GlobalSectorList.Size() > nearstart)
         {
-            short edx;
+            int edx = 0;
 
             for (unsigned i = nearstart; i < GlobalSectorList.Size(); i++)
             {
@@ -697,8 +697,8 @@ int GetAngleToSprite(DExhumedActor* a1, DExhumedActor* a2)
     if (!a1 || !a2)
         return -1;
 
-	auto pSprite1 = &a1->s();
-	auto pSprite2 = &a2->s();
+    auto pSprite1 = &a1->s();
+    auto pSprite2 = &a2->s();
 
     return GetMyAngle(pSprite2->x - pSprite1->x, pSprite2->y - pSprite1->y);
 }
@@ -708,8 +708,8 @@ int PlotCourseToSprite(DExhumedActor* pActor1, DExhumedActor* pActor2)
     if (pActor1 == nullptr || pActor2 == nullptr)
         return -1;
 
-	auto pSprite1 = &pActor1->s();
-	auto pSprite2 = &pActor2->s();
+    auto pSprite1 = &pActor1->s();
+    auto pSprite2 = &pActor2->s();
     int x = pSprite2->x - pSprite1->x;
     int y = pSprite2->y - pSprite1->y;
 
diff --git a/source/games/sw/src/cheats.cpp b/source/games/sw/src/cheats.cpp
index d26c43721..ec4035484 100644
--- a/source/games/sw/src/cheats.cpp
+++ b/source/games/sw/src/cheats.cpp
@@ -160,7 +160,7 @@ bool WarpCheat(cheatseq_t* c)
     if (TEST(pp->Flags, PF_DEAD))
         return true;
 
-	DeferredStartGame(maprec, g_nextskill);
+    DeferredStartGame(maprec, g_nextskill);
     return true;
 }
 
diff --git a/source/games/sw/src/game.cpp b/source/games/sw/src/game.cpp
index 01317a4ac..d5f3bcd19 100644
--- a/source/games/sw/src/game.cpp
+++ b/source/games/sw/src/game.cpp
@@ -219,7 +219,7 @@ void GameInterface::app_init()
     for (int i = 0; i < MAX_SW_PLAYERS; i++)
         INITLIST(&Player[i].PanelSpriteList);
 
-	LoadCustomInfoFromScript("engine/swcustom.txt");	// load the internal definitions. These also apply to the shareware version.
+    LoadCustomInfoFromScript("engine/swcustom.txt");	// load the internal definitions. These also apply to the shareware version.
     if (!SW_SHAREWARE)
         LoadCustomInfoFromScript("swcustom.txt");   // Load user customisation information
  
diff --git a/source/games/sw/src/game.h b/source/games/sw/src/game.h
index 08d2a313e..19b297f50 100644
--- a/source/games/sw/src/game.h
+++ b/source/games/sw/src/game.h
@@ -854,6 +854,14 @@ struct PLAYERstruct
         PANEL_SPRITEp Next, Prev;
     } PanelSpriteList;
 
+    // hack stuff to get a working pointer to this list element without running into type punning warnings with GCC.
+    // The list uses itself as sentinel element despite the type mismatch.
+    PANEL_SPRITEp GetPanelSpriteList()
+    {
+        void* p = &PanelSpriteList;
+        return reinterpret_cast<PANEL_SPRITEp>(p);
+    }
+
     // Key stuff
     unsigned char HasKey[8];
 
diff --git a/source/games/sw/src/interpso.cpp b/source/games/sw/src/interpso.cpp
index eac8e1215..95fafe0ff 100644
--- a/source/games/sw/src/interpso.cpp
+++ b/source/games/sw/src/interpso.cpp
@@ -97,12 +97,15 @@ static int &getvalue(so_interp::interp_data& element, bool write)
     case soi_sprx:
 		if (element.actorofang)
 			return element.actorofang->s().x;
+        break;
     case soi_spry:
 		if (element.actorofang)
 			return element.actorofang->s().y;
+        break;
     case soi_sprz:
 		if (element.actorofang)
 			return element.actorofang->s().z;
+        break;
     default:
 		break;
     }
diff --git a/source/games/sw/src/lists.h b/source/games/sw/src/lists.h
index bb4971395..05130fd46 100644
--- a/source/games/sw/src/lists.h
+++ b/source/games/sw/src/lists.h
@@ -39,22 +39,21 @@ typedef
     struct List *Prev;
 } LISTHEAD, *LIST;
 
-#define FIRST(list)        (list->Next)
-#define LAST(list)         (list->Prev)
+inline void INITLIST(void* listp)
+{
+    LIST list = (LIST)listp;
+    list->Prev = list->Next = list;
+}
 
-
-#define INITLIST(list)          ( ((LIST) list)->Prev = ((LIST) list)->Next = (LIST) list)
-
-
-#define INSERT(list, nodep)  ( ((LIST) nodep)->Prev = (LIST) list,         \
-                               ((LIST) nodep)->Next = ((LIST) list)->Next, \
-                               ((LIST)  list)->Next = (LIST) nodep,        \
-                               ((LIST) nodep)->Next->Prev = (LIST) nodep)
-
-#define INSERT_TAIL(list, nodep)  ( ((LIST) nodep)->Next = (LIST) list,  \
-                                    ((LIST) nodep)->Prev = ((LIST) list)->Prev, \
-                                    ((LIST)  list)->Prev = (LIST) nodep,        \
-                                    ((LIST) nodep)->Prev->Next = (LIST) nodep)
+inline void INSERT(void* listp, void* nodepp)
+{
+    LIST list = (LIST)listp;
+    LIST nodep = (LIST)nodepp;
+    nodep->Prev = list;
+    nodep->Next = list->Next;
+    list->Next = nodep;
+    nodep->Next->Prev = nodep;
+}
 
 inline void REMOVE(PANEL_SPRITEp nodep)
 {
@@ -62,11 +61,11 @@ inline void REMOVE(PANEL_SPRITEp nodep)
     nodep->Next->Prev = nodep->Prev;
 }
 
-#define TRAVERSE(l, o, n)    ASSERT(((LIST)l)->Next && ((LIST)l)->Prev); for (o = (decltype(o))(((LIST)l)->Next);      \
-                                                                              n = o->Next, (LIST) o != (LIST) l; \
-                                                                              o = n)
-
-#define EMPTY(list)          (((LIST) list)->Next == (LIST) list)
+inline bool EMPTY(void* listp)
+{
+    LIST list = (LIST)listp;
+    return list->Next == list;
+}
 
 END_SW_NS
 
diff --git a/source/games/sw/src/panel.cpp b/source/games/sw/src/panel.cpp
index 8b9a492c8..d29cedb05 100644
--- a/source/games/sw/src/panel.cpp
+++ b/source/games/sw/src/panel.cpp
@@ -116,9 +116,10 @@ void pNullAnimator(PANEL_SPRITEp)
 
 PANEL_SPRITEp pFindMatchingSprite(PLAYERp pp, int x, int y, short pri)
 {
-    PANEL_SPRITEp psp=nullptr, next;
+    PANEL_SPRITEp next;
 
-    TRAVERSE(&pp->PanelSpriteList, psp, next)
+    auto list = pp->GetPanelSpriteList();
+    for (auto psp = list->Next; next = psp->Next, psp != list; psp = next)
     {
         // early out
         if (psp->priority > pri)
@@ -135,9 +136,10 @@ PANEL_SPRITEp pFindMatchingSprite(PLAYERp pp, int x, int y, short pri)
 
 PANEL_SPRITEp pFindMatchingSpriteID(PLAYERp pp, short id, int x, int y, short pri)
 {
-    PANEL_SPRITEp psp=nullptr, next;
+    PANEL_SPRITEp next;
 
-    TRAVERSE(&pp->PanelSpriteList, psp, next)
+    auto list = pp->GetPanelSpriteList();
+    for (auto psp = list->Next; next = psp->Next, psp != list; psp = next)
     {
         // early out
         if (psp->priority > pri)
@@ -154,11 +156,12 @@ PANEL_SPRITEp pFindMatchingSpriteID(PLAYERp pp, short id, int x, int y, short pr
 
 bool pKillScreenSpiteIDs(PLAYERp pp, short id)
 {
-    PANEL_SPRITEp psp=nullptr, next;
+    PANEL_SPRITEp next;
     bool found = false;
 
     // Kill ALL sprites with the correct id
-    TRAVERSE(&pp->PanelSpriteList, psp, next)
+    auto list = pp->GetPanelSpriteList();
+    for (auto psp = list->Next; next = psp->Next, psp != list; psp = next)
     {
         if (psp->ID == id)
         {
@@ -327,7 +330,6 @@ void PlayerUpdateHealth(PLAYERp pp, short value)
 
 void PlayerUpdateAmmo(PLAYERp pp, short UpdateWeaponNum, short value)
 {
-    USERp u = pp->Actor()->u();
     short x,y;
     short WeaponNum;
 
@@ -924,7 +926,8 @@ void RetractCurWpn(PLAYERp pp)
         else
         {
             // check for any outstanding siblings that need to go away also
-            TRAVERSE(&pp->PanelSpriteList, cur, nxt)
+            auto list = pp->GetPanelSpriteList();
+            for (auto cur = list->Next; nxt = cur->Next, cur != list; cur = nxt)
             {
                 if (cur->sibling && cur->sibling == pp->CurWpn)
                 {
@@ -6410,7 +6413,8 @@ InsertPanelSprite(PLAYERp pp, PANEL_SPRITEp psp)
     }
 
     // search for first pri in list thats less than the new pri
-    TRAVERSE(&pp->PanelSpriteList, cur, nxt)
+    auto list = pp->GetPanelSpriteList();
+    for (auto cur = list->Next; nxt = cur->Next, cur != list; cur = nxt)
     {
         // if the next pointer is the end of the list, insert it
         if ((LIST) cur->Next == (LIST) &pp->PanelSpriteList)
@@ -6568,7 +6572,7 @@ void
 pDisplaySprites(PLAYERp pp, double smoothratio)
 {
     USERp u = pp->Actor()->u();
-    PANEL_SPRITEp psp=nullptr, next=nullptr;
+    PANEL_SPRITEp next=nullptr;
     short shade, picnum, overlay_shade = 0;
     double x, y;
     unsigned i;
@@ -6580,7 +6584,8 @@ pDisplaySprites(PLAYERp pp, double smoothratio)
     double const look_anghalf = pp->angle.look_anghalf(smoothratio);
     double const looking_arc = pp->angle.looking_arc(smoothratio);
 
-    TRAVERSE(&pp->PanelSpriteList, psp, next)
+    auto list = pp->GetPanelSpriteList();
+    for (auto psp = list->Next; next = psp->Next, psp != list; psp = next)
     {
         ang = psp->rotate_ang;
         shade = 0;
@@ -6856,9 +6861,10 @@ pDisplaySprites(PLAYERp pp, double smoothratio)
 void
 pSpriteControl(PLAYERp pp)
 {
-    PANEL_SPRITEp psp=nullptr, next=nullptr;
+    PANEL_SPRITEp next=nullptr;
 
-    TRAVERSE(&pp->PanelSpriteList, psp, next)
+    auto list = pp->GetPanelSpriteList();
+    for (auto psp = list->Next; next = psp->Next, psp != list; psp = next)
     {
         // reminder - if these give an assertion look for pKillSprites
         // somewhere else other than by themselves
diff --git a/source/games/sw/src/sector.cpp b/source/games/sw/src/sector.cpp
index 0319ac290..566f570f0 100644
--- a/source/games/sw/src/sector.cpp
+++ b/source/games/sw/src/sector.cpp
@@ -2192,7 +2192,7 @@ OperateContinuousTrigger(PLAYERp pp)
     if (pp->cursectnum < 0)
         return;
 
-	switch (sector[pp->cursectnum].lotag)
+    switch (sector[pp->cursectnum].lotag)
     {
     case TAG_TRIGGER_MISSILE_TRAP:
     {
diff --git a/source/games/sw/src/sprite.cpp b/source/games/sw/src/sprite.cpp
index afabc277b..8af579946 100644
--- a/source/games/sw/src/sprite.cpp
+++ b/source/games/sw/src/sprite.cpp
@@ -1861,11 +1861,11 @@ SpriteSetup(void)
     PicAnimOff(PLAYER_NINJA_RUN_R0);
 
     // Clear Sprite Extension structure
-    memset(&SectUser[0], 0, sizeof(SectUser));
 
     // Clear all extra bits - they are set by sprites
     for (i = 0; i < numsectors; i++)
     {
+        SectUser[i].Clear();
         sector[i].extra = 0;
     }