Hey, that was pretty fun to play! Let me drop in some critique, if you don't mind.
Positive:
-The character designs are very fun! I definitely want to see what happens with this quirky duo. Would absolutely love to play a game with them featuring as protragonists.
-The exploration was pretty cool. It was nice to have all these side areas to explore and get more power ups and health pickups.
-The platforming aspect was alright. I really like the use of walljumps and jumps.
The negative:
-Combat could use a bit of work, specialy on the defense department. By that I mean: it's very difficult to dodge the enemy projectiles since: a) Zarboog jumps very little. b) Zarboog can't crouch (can't count the amount of times I was hit by a extremely slow moving laser to my face) c) the enemy projectiles move through the walls. All that combined forced me to more often than not having to retreat constantly and preemptively fire to hopefuly kill enemies before facing them. I think that if you improve on either of these three areas the combat will improve a lot!
-The flying enemies perhaps should keep their distance. The fact that they track the player means that they eventualy can catch up to you and trap you. I would suggest you to modify their chase function so when they are close enought to the player, they stop chasing... but when they are again far from the player, they chase again.
-The difficulty seemed a bit inconsistent for some jumps. For example: At the beginning of the level you gotta risk losing one life for the sake of getting one extra life in a series of jumps that I think are the hardest in the level. Then there were way too many leaps of faith. I'd suggest you to address that by making jumps clearer: maybe a line of pickable floating coins can indicate where you have to jump or maybe move the platforms closer so the camera con show the player where he's supposed to jump.
I know it's very early, but here are a couple of suggestions:
-Add pickus! Like coins, powerups and much more! You'll see the fun factor will duplicate tenfold!
-Add more animations for the characters! Zarboog is brimming with charisma, but maybe some more for some other situations, like using different animations from jumping off walls, a more lively idle animation... heck, maybe one where Zarboog is tired if his health is very low.
-Add more to the platforming: maybe Zarboog learns to double jump, maybe Pleeb can liftt Zarboog up and they can both glide, etcetera.
-Perhaps use your own tileset? The styles were clashing a bit between the characters and the environment.
Of course, I had my fun with it. I definitely see that there's quite the potential here! Keep it up, and good luckl