Although this game sure reminded me of the old times, it's done with graphics and sound, certainly not gameplay. This game is EXTREMELY easy. I was trying to use weapons tactically, conserve ammo, learn enemy patterns... until I've met with the first boss. Then I realized that firing away everywhere with everything you've got works just fine AND is way faster. And by that time speed became crucial to me, because I grew BORED. The levels look all the same, new features are introduced very rarely, even new enemies appear only so often. Thrashing everything on my way indeed boosted my fun-o-meter... for a few levels. You can't just put a lot of different weapons and pretend it's fun. This just doesn't work if the enemies are boring. I mean, their AI sure is interesting, it's fun to watch practically the same enemy grow more abilities or wondering "What's that new guy capable of?" But all of this goes straight out the window if the enemy can't even show off it's awesomeness because you've obliterated it the moment it appeared. And the numbers don't help either, the difference between one enemy and a dozen is 2 seconds and a handful of health pickups.
Speaking of health pickups. There's an abundance of those. No, you know what? Let me rephrase this. There's a F*CKING LOAD of those. Every fifth of so enemy drops a +5 to your health when they can't even get close to you to do any damage. An occasional projectile and quake-like excessive health decrease are the only things that stop you from getting your health to thousands. I ended the last boss battle, the supposedly hardest battle in the game, with 290 (!) HP. (That's my personal record) This completely ruins the thrill of a difficult boss.
And the bosses here are anything but difficult. Even if they attack, I didn't even notice it. The only thing they do is spawn minions. How the hell is it different from your ordinary level then?
Level design is uninteresting, repetitive and doesn't give any challenge at all. I mean, what's the point of the platforms above the pit if you not only don't die from falling down, don't even lose HP, cheerily jumping back up? No point, exactly. The whole world consists of the same platforms that come in exactly two (or so it seemed) colors, exactly three breakable walls and exactly two places where you have to dig your way down. Wow, so interesting. How exactly is it fun for more than five levels? Music isn't helping, too, because there are 3.5 tracks in this game, substituting each other every level. It doesn't set the mood, it doesn't liven things up, it's just... there.
Now, I don't mean to be harsh, I'm just pointing out the flaws. Your game needs to be livened with different interesting areas because the view of leaves and trees bores really fast. The enemies need to be fine-tuned, they need to be a lot more threatening. How about increasing their damage significantly instead of increasing numbers? That will fix the problem with abundance of health, too. Bosses need to be way more interesting because the way I saw it, they were just hanging around spitting lesser enemies without actually posing any threat themselves. This needs to be fixed. The robot boss has what looks like cannons - why not give him a couple of arc attacks? Or, maybe, a badass beam obliterating everything near the floor, but there would be platforms for you to dodge it?
This game could be so much better. Maybe next time?