I'm pretty sure
Primal Rage requires at least 1MB Chip, not sure if it needs 2MB. Most people assumed it was an AGA-only game because it wouldn't boot on their stock A500. The demo of Speris Legacy will run on a 2MB Chip OCS/ECS Amiga, and the full game of that is definitely for AGA machines only.
There would be a few games out there than need all 2MB, but not many. The main advantage you'll get from the extra ChipRAM is the amlunt of screens and windows you'll be able to have open at the same time in Workbench. You could work on much larger images in paint programs, load in larger sound samples and mods, and just feel generally comfortable with knowing you're not going to run out of Graphics Memory while you're running a bunch of programs. ChipRAM also gets used as regular system Memory when your FastRAM runs out (or it's always used if you don't have FastRAM) so it will generally increase your chances of being able to run anything, not just programs and games that need extra ChipRAM, but anything that requires more than 1MB at all to run!