Nuclear Winter v1. Watch the game for 10 minutes and the debug log is full of this.
[t=00:26:14.939325][f=0028280] Error: [LuaRules::RunCallInTraceback] error=2 (LUA_ERRRUN) callin=DrawWorldPreUnit trace=[Internal Lua error: Call failure] [LuaUtils::InstanceDataFromGetData] Non-existing UnitID (24851) is supplied
http://zero-k.info/Battles/Detail/2335963