Its been a while since ive followed the arduboy and when i last saw it (in its closed beta-ish phase were people were getting really early copies) the thing could only hold a single game and you had to switch it via your computer. is this still the case nowadays?
There has been no change.
I have seen some buzz about creating a new Arduboy design with a sd card slot. My Arduino Zero based system - The next generation Arduboy?
Someone was working on an Android app for flashing Arduboy games. WIP: Android App that flashes games via OTG [Arduboy Mate]
You could make a game that contained multiple games like this one.
As long as you had enough memory you could combine a couple games and a custom game selector for those games by making them a single game. Though I think the best option would be just having a smart phone or maybe even something like PocketC.H.I.P, or other small devices that can run the various different programs for flashing games to the Arudoby that you can just take with you.