Tiger Electronics Pocket Arcade LCD game. This one is supposed to represent Sonic 3, but of course doesn't. It was fairly difficult to play, simply due to trying to figure out what was going on as various things would appear all over the screen. You could summon Tails a certain number of times by pressing a button, but it's hard to tell what exactly he did.
There is another Pocket Arcade for NiGHTS as well, but I never managed to find it.