It's because the game is by Aspect, a company that Sega outsourced a bunch of later Game Gear platformers to. Unfortunately, Aspect never managed to make a good game, at least not on the Game Gear they sure didn't. Some people like a few of their GG games, but I think they're mediocre at best, and are mostly bad.
Aspect developed all of these Game Gear games that were published by Sega:
-Sonic the Hedgehog 2 (bad, particularly on GG)
-Sonic Chaos (average)
-Sonic Triple Trouble (mediocre, same as chaos)
-Sonic Blast (poor)
-Tails' Adventure (probably their best GG game)
-Legend of Illusion starring Mickey Mouse (the game is slow and mediocre to bad)
-Deep Duck Trouble starring Donald Duck (another slow and subpar platformer, much like Legend of Illusion)
-Coca-Cola Kid (Japan-only release, supposedly okay-ish)
-Ax Battler: The Legend of Golden Axe (the bad Zelda 2-style Golden Axe game)
-Virtua Fighter Mini (mediocre)
-The Lost World: Jurassic Park (terrible, super-short game)
-Batman Returns (another bad licensed platformer)
-Tama and Friends (Japan-only, no idea about this one but I doubt it's good)
With games like those making up a substantial chunk of Sega's first-party Game Gear library, it's no wonder that the GG's game quality level was so suspect so much of the time... I wish Sega hadn't done much of anything with Aspect. The only GG Sonic game I definitely like is the first one, Sonic the Hedgehog, which was done by Sega itself. Sega or better external teams also did the first two Mickey (Illusion) games for the GG, both of which are fun, the first Donald game, which is decently entertaining, and the few good later first-party-published Game Gear platformers, such as Zenki (JP only) and Ristar. But Aspect... the closest they got to "good" is Tails' Adventure and Sonic Chaos, and I don't know if either one quite makes it.
