They should work unless they are programmed badly and do things such as writing to undefined OCS registers/bits that now have a meaning in ECS and generally assuming things (such as bitplanes) to be in a certain place at all times.
Most games have more trouble with Kickstart 2.x than with the chipsets. Sometimes a kickstart switcher or degrader program can help.
In short, properly written programs should work fine, but it is trial and error I'm afraid, especially for games that don't run from Workbench.
