Smooth controls, satisfying gameplay, depth and a good challenge. Excellent game sir!
my only critiques
1.your main character is dark orange, your bullets are orange, enemies are orange and enemy debris is dark orange. it very easy to lose track of your character amongst all the explosion. could you change his colour to a perhaps a blue to make him stand out? or make the explosions take up less room on screen.
2. all the upgrades are quite useful except speed, the increase in speed per point is just not significant enough to justify spending it there as opposed to somewhere else. maybe boost that up a little?
now here is the tid bit for all those struggling to get high scores.
1. increase bullet damage increases bullet damage by 1 per projectile...its only good for really wiping out the small guys (get damage to 4 per shot and the little guys will just be melting, no real need to go beyond that), big enemies just have too much health later on for this to be your primary source of damage.
2. increase grenade increase your stock grenade amount AND damage done per grenade (I think max is 20 grenades, 240 damage per grenade)...decent damage...you can almost rely on this as a primary source later on but you will of course eventually run out..so not so reliable...still useful however.
3. increase lives is increase lives...not so important unless you taking risks but you will only really be doing that due to 4.
4. increase stomp damage...this DOUBLES stomp damage PER point so 80 turns to 160 - 240 - 480! ect. this will one shot all enemies (kills the final boss in like 8 stomps!). there is no cool down for stomps and thus this is what you use later stages in the game, but of course, miss a stomp, hit in the wrong area and you lose a life...hence why 3 is so useful. THIS is how you get high scores ;)
5. ;( just cant find a use for this. you might think it helps you get power ups but the speed increase is just so negligible it does not really help that much.
I wish it was longer, but that can be said about anything one enjoys. A nice bite sized piece of fun. thank you :)