Long story short, they were. I feel bad for it because it has so much variety and colour to it, but the game doesn't really work for reasons including but not necessarily limited to the following:
- The Duke Nukem engine, specifically the way that everything moves on an 8x8 grid. This worked noticeably better for Duke, and I'm not totally sure why - part of it is that Duke had enemies that ignored the grid and moved smoothly, whereas Cosmo doesn't. Combined with this, Cosmo has to get a lot closer to enemies rather than shooting them at a distance - he has to jump on them (often multiple times) with his only distance attack being bombs that are fairly rare (and that have to be set close to the enemy anyway if it's stationary!) Perhaps it's also at odds with the console-style platformer presentation that Cosmo is going for - it's noticeably janktastic compared to its counterparts.
- No vertical visibility. 200 pixels isn't much in the first place, but the status bar takes up a quarter of that - on the ground you can look up and down, but during even quite short jumps there's no way to see what you're landing on. The game tries to remedy this by placing pickups in arcs to guide your jump, but trusting them is a mistake - look at the cluster of red fruit near the right hand side of the map. You can't see the bottom of the level from the ledge, and so it's easy to assume there's ground under there and walk off to instant death. I did it twice.
- Combined with that, there are too many bottomless pits - the levels might not look long in the maps, but they encourage exploration so progress can be slow through them, and it's very easy to lose all of it with one slip.
- And the lack of health in general! You get four hit points by default, and that number can be extended, but health upgrades are few and far between. When you switch levels, fall off the bottom of the screen or otherwise die, it doesn't even restore your motherwanking hit points - if you entered a level by the skin of your teeth, you'll start in that state again if you die at any point during it.
And while not a flaw, I want to repeat that it's strange that the game is called "Forbidden Planet" on all three of the episode title screens, and that the name "Cosmo's Cosmic Adventure" is only mentioned on a startup card before it along with the Apogee logo. Perhaps there were intended to be more cosmic adventures at some point?
I only played through the first episode and the second two are reputedly much harder... I'll see how long it is before I give up.
xyzzysqrl offers a second opinion here, which is quite similar to this opinion because it's correct.