This game is frustratingly close to being really good. Like the presentation's great, the character switching mechanic is very original and works well, and the level design is pretty good for the most part. But there are two problems that just fuck it all up:

1. The jumping control isn't all that tight. You don't really notice until you try to get into tricky areas or on small platforms, but the jumping just doesn't feel quite right, and it's really frustrating when you end up dying in a way you wouldn't have in a Mario game or something.

2. The worst problem is the hidden key mechanic. Basically, in each world, you need to find a special key to unlock the door to the boss. But there aren't any hints to where these are, and the hiding places seem pretty random. You can only find them by shooting just the right spot, so unless you look up their locations, your best course of action is just to be constantly shooting at everything on every stage and hope that it wasn't in a tiny space between a couple of your shots. It makes the whole thing frustrating and tedious, but if you look it up, then it removes any need to play half the stages in the game. This more than anything else stops the game from being great.

It's still not a bad game, and it might be worth picking up if you're a big platformer fan, but you can do better on the PC Engine.