You sure should get Microcosm,as it is THE game for the CD32. Imagine alls this introvideo playback and the levelbackground streamed directly from CD on a machine that exceeds the specs of an bare A1200 only in one Point: the Akiko-chip.
Rise of the Robots is nice too, gameplay isn`t that good, but graphics are nice plus you don`t have to wrestle with the 20 or so disk of the A1200/A4000 Version.
AlienBreed TowerAssault has a real cool an long intro in addition to the normal disk version.
No CD32 is halfway complete without Wingcommander. It is a little slow, but it is the AGA-version that never made it to floppydisk.