I recall Fokker Triplane needed System 4.1, and that war game with the digitized sound for 128K/512K machines also used a very early release of System software - but it was probably to minimise RAM usage to run the game in the first place.  I suspect the version of Dark Castle II I have is very early, as surely that's one of the games that would run fine in System 7.  But the version I have needed System 5 (it came with a boot disk) again perhaps for lower resources to run it on a 1MB Plus.