How do I play these games?

Unless you own original hardware (chances are you don't), your best bet is using an emulator. Since the CD-i was never a particularly popular gaming system, emulators are not nearly as plentiful and mature as for other systems. As of today, the best recommendation is to use MAME (or Mess for older versions). You will need a compatible CD-i player BIOS file (cdi200.rom will do). Games requiring the system's optional MPEG module are not yet supported.

As you can see, we don't have decent instructions here yet. If you have questions or if you want to help fill this gap, head over to the forum.