There's a lot to like about Ultonions: the bright retro graphics, the chip'ish music and even the sexuliased 80s heroine. But... The gameplay is not quite bad but the design aimed for retro and ended up with unresponsive instead.
You can aim in only 4 directions, left, diagonal left/up. right and diagonal right/up. It would have been better as an 8-way scheme. Or even just up - I want to shoot up.
You can shoot or walk, not both. And you walk slowly. This may be a side effect but quickly swinging round to shoot and swinging back again seem to stick. This is incredibly annoying when dealing with fast moving flying enemies.
The crouch animation is unusually long, you must wait for it to finish before firing or walking again. Popping down to shoot and popping back up to jump and dodge stuff is not going to happen.
About a fifth of your view is obscured on the left and right by the decorative interface. This makes the dino-riding stage particularly vexing as you can't see what's coming.
I cramped my thumb trying shoot fast - I haven't managed that since I had a Commodore 64. Not sure if this is a good or bad point.
I'm not recommending this but is a weak non-recommendation. Learning from your mistakes is big part of the game and that's good reto but not having the space to see or control responsiveness to react is bad retro. Games like Thundercats, Mask and Turrican all got this right 30 years ago - Ultonious really should have too.