Start a multiplayer game on the map `op4ctf_hairball`. It's a very small map - choose any team and walk onto the slippery ice in the middle. You will never stop sliding around. This is a bug introduced within the past decade of game updates.
There is an ifdef for Win32 in the function that makes it so only Windows compiles can save stats. The function would need to be edited to work across all supported platforms.
## Missing official maps
Sierra's website provided official ports of a few HL maps to OP4. These were never provided with the Steam release of Half-Life: Opposing Force.