All too easy.
For best results: Buy the sub machine gun when you have enough and put a point into pierce and damage. Then save up for the machine gun (don't worry about the other guns, you can buy them later if you really want) and put all your extra points in machine gun. There, that was easy.
That's it?
You should better add health and reload upgrades cause all weapons except pistol are lame so there's no pint upgrading those. Since there are more and more better enemies I'd like to stay alive longer right?
Not bad, but....
Its a good basis for a game but you need more guns maybe grenades. heck even a upgradable turret would be nice. All im sayin is I had all this money and nothing to spend it on after I bought out the armory. so all in all good game just could use some expanding.
Above 'okay'.
There are a few issues I have with this game.
1) The money system is practically worthless, I bought all of the weapons like 3 or 4 rounds before the end, I wasn't counting. I think it would have been more effective to allow the user to spend money on upgrades, rather than only getting 1 point per wave. As it is currently, you pretty much have to invest everything you have into one weapon.
2) The Sniper Rifle is way too overpowered, since even non-headshots will still almost kill enemies, even without damage upgrades. I think other weapons should be made more powerful for body-damage, and the sniper rifle should be for people who are confident in their aim.
3) The bloody screen effect only really works in FPS games, and even then it's kinda annoying. Especially when you have enemies spawning from the left side of the screen and you can't see them because the screen is covered with blood. It would probably be more effective to have a health bar at the top of the screen that flashes when it gets low, since alerting the player that they're about to die is important. I just think you did it the wrong way.
4) The weapon variation was pretty shallow. There was a pistol, a sniper rifle, and 3 automatic weapons that function at different ranges. How about shotguns for when a bunch get close? Or heck, maybe grenades and/or flamethrowers?
so, what's the backstory?
Soldier: "General, we've almost won. There's only a single enemy left, hunched up next to those explosive barrels. Should I just shoot the barrels?"
General: "Soldier, don't even think about it. You're not trained to handle explosives!"
Solider: "Alright. We'll have a Sniper climb that bilding over there and take him down."
General: "Enter an unknown building? Are you insane? We don't know if the building is up to code. It might collapse any second."
Soldier: "Maybe we could send a scout squad to circle around him and take him out from behind?"
General: "What? You want to send our troops behind enemy lines? That's stupid! Attack from the front!"
Soldier: "Alright. I'll send in all our troops to storm the enemy."
General: "ALL of them? What if this is an ambush? No no, send in a small team first, to determine if it's safe."
Soldier: "*sigh* alright, commencing Wave 1.."
General: "That's better. And don't forget to sell him some new weapons now and then. This guy will make me rich! $$$"
Was still fun once, but it's hardly original.