Had a problem getting the built-in windows zip manager to handle the file. 7zip opened it, but it's something you probably want to look into.
I used the "maximum compression" scheme in WinRAR, it's maybe that.
Gameplay was entertaining, but I do have a number of (hopefully constructive) criticisms.
1) The background felt a little TOO bland. Another layer or two of parallaxing stars, grids, glowing neon circuitry, or whatever would have added some visual appeal and helped further sell whatever theme (Tron, Matrix, space combat?) you were going for.
True. I played a lot of other arena shooters recently and I must admit I have one of the less appealing visually. In the other hand, too much impressive sounds and too much particles in some arena shooters annoys me after 10 min.
2) The powerups were difficult to tell apart and difficult to grab. I don't know what a lot of them did (cell?), and some of them seemed / were actively bad (size+, trap). Weapon+ and life were the only ones I ever actually wanted.
I think I'll remove speed+ and cell (cell increase energy by 1, it's boring)
size+ is not bad since it makes you less vulnerable to missiles. It also makes you slower so it's not that desirable.
3) Tooltip on death says "You can give away traps." How?
You must fly near ennemies hoping that they'd catch your trap. To catch someone else powerup, one must be nearer than the owning ship from to the powerup.
Note that ships can grab a powerup directly by touching them. So you can touch an ennemy with your trap to kill him without shooting.
OK, it's not well explained like many other things in the game.
4) It would be nice if enemies pinned themselves to the edges of the radar. A few times on levels 1-3 the last enemy escaped and I had a difficult time tracking it down because I wasn't watching what direction it fled.
Agreed, it also annoys me

.
5) The "pts / max" thing was pretty incomprehensible. It seemed to be related to the max number of upgrades you could grab for a given level? No feedback on how much of that you're using or when you've hit the limit until you're unable to grab new items.
It's just a score / best score counter, I could remove that if it's confusing.
6) The powerups also felt a bit underwhelming - was it part of your design that it should take a long time to make your ship into a juggernaut? I think I'd prefer if most of the stuff were temporary but impressive items like burst and bullet time - temporarily supercharged battery regeneration or a much much improved gun for 10-15 seconds would be more fun (IMO) than small incremental upgrades.
You're true. I realized that only yesterday. I'm thinking about gravity bombs...
7) AI were annoyingly good at snagging grabbed items I was dragging behind me except when they were traps.
You were unlucky or too far from them. Make sure the opponent is nearer to the powerup than you.

Player bullet velocity = player velocity + base velocity made aiming tricky. Ok, so for me it was impossible except when I lined up behind a fleeing ship and unloaded on them.
I can't really remove that. The gameplay is really based on inertia (you "catch" powerups, bullets are a guided...) and i think that's the interesting.
If the bullets were more like velocity = k * player velocity + base velocity with 0 <= k < 1 it wouldn't allow to shoot forward when going forward, unless by increasing base velocity too much for my taste.
The only thing i can change is the base velocity, that i already increased because this problem annoys people.
Maybe with a less dull background pleople would have less problem with inertia.
There is also the secret ALT button which allow to strafe.
Actually i like that killing an ennemy is not that straightforward, and bullets are slow (and cost energy).
9) Only used turbo, like, once. I suppose it might be good for dodging bullets, but most of the time I ended up flayed by head-on barrages.
I find the turbo actually useful.
10) You can die really quickly against upgraded opponents even with double-overcharged life.
Yep. You have to take some size+ to be more solid.
It's important to me that the very same sets of rules apply to opponents and you. Only exceptions in the current game are:
- opponents' bullets are less guided than the player's ones
- opponents cannot trigger a bullet time
- the player's bullet are faster
Please don't take these comments as saying I hated your game. I liked it and I played it for at least half an hour before I ended up dying repeatedly around level 17. It could just use a bit more polish.
Don't be sorry at all.
It is incredibly useful to have such a feedback. I agree with most things you said and it made me realize how the game could appear. Thanks a lot.
I need to stress why the game is what it is. It's a quite direct port of an older DOS game i made when i was younger. I ported it to revive it, few things in gameplay are different now, but i'm so used to this gameplay i can't see the flaws.
I think it will mostly remain unpolished and eventually i'll make another arena shooter, because the current code is pure crap and would need a lot of refactoring to allow changes.