I got this in The Green Light Bundle's 'Best of' Bundle. It took around 10 hours to get to the end, no 100%.
I heard the comparisons to Super Smash Bros. and Custom Robo and didn't believe it at first, but it got me interested in the game. And I'm really glad I picked this up now.
So you're a super fighting robot, and it's your mission to go beat up other robots in the Levels and beat the boss at the end of the third stage of each Level. Controls felt pretty tight. On a controller, left stick moves, you have a button for jump, normal attacks, special attacks, and the parts menu. You can wall jump, sprint, double jump, and have a variety of normal attacks based on tilting the stick or if you're in the air (no smash attacks here). But the rest of the fancy stuff comes from parts.
Megabyte Punch is part exploration, part platformer, part fighter, part collectathon. The basic premise of the game is to find the door in each stage to advance to the next section until you get to the end of the third stage and fight the boss to clear the level. On your way, you'll fight other custom-made robots both in the field and in arenas that seal themselves off when you enter. Like Smash, you still have to raise the unseen damage number for your enemies, and like Smash, a particularly hard hit will send them flying. But if your foe slams into a hard surface, it explodes, leaving behind life-granting Bits or a custom part. Or if they go into the soft blocks, they'll cut right through them and explode. And the same applies to you.
Boss battles twist the basic formula and turns it into an itemless match of Smash. Smack the boss around and get his damage up and then send him into the black killzones around the area a few times. And of course, try not to burn all your lives in the process, or you'll have to start the entire level over.
I liked exploring, though outside of the forced-fight arenas, you're allowed to rush to the end. The issue then is finding the right way to go. The damage you take is permanent until you die and respawn, so rushing may end up being the better option for some. You can carry a small inventory of extra parts from the robots you destroy and from there you can swap out with what you currently have on, but everything not equipped goes to your inventory at home when you go through any door. You more or less start each stage with the clothes on your back, but you can break down any spare parts for Bits--64 of which give an extra life, and you start each Level with three no matter what.
I wouldn't say the platforming was necessarily hard, but I went with more jumps and most of the challenge was maneuvering around obstacles with enemies present, or dealing with dangers like damage plates and mines in the arenas. Each stage is pretty big though, especially if you try to drill through the soft blocks.
Parts do a variety of things, like give you passive mobility boosts or extra jumps, or some give you special attacks you assign to Neutral, Up, Down, and Side B. While there are a lot of parts, there aren't as many unique effects, but you could argue it's partly for aesthetics reasons too. You can equip to your torso, head, shoulder, left and right arms each, left and right legs each, and hips. And there are color palettes to collect too, though you can't customize each part's color--it's everything or nothing. You can save quite a few parts and color loadouts too.
Progression in specials felt a little stagnant, but it was less "ever-powerful moves in later stages" and more "everyone is mostly on the same playing field." The strongest special is the 25-damage Megabyte Punch, and I had a move that did 18 in the first level, though it was slow coming out. Every move felt like it had a use, as opposed to 100 moves of which you'd use 10 at best.
Overall, if you enjoyed Adventure Mode/Subspace Emissary in Smash, you'd probably like this game. It has local 2-4 coop for Adventure, there's Versus, and a Tournament Mode to get rare parts. No online, but desyncs and lag would hamper enjoyment for a game like this. Lots of parts, lots of things to beat up, great length for the price.
And I had a smile on my face from the first time I spiked one of those little robots through the ground.