TDZSG

WASD - Movement
R - Reload
F - Melee
G - Dynamite
LMB - Shoot
LSHIFT - Sprint
P - Pause game
N - Next Wave (Post-Compo)
, (comma) - Decrease volume
. (full stop) - Increase volume
ESC - Restart game (No prompt!)

Ammo +10 - 1$
HPPack costs relative to your missing health
Dynamite - 5000$

A few more things you should know:
When you sprint you become half as fast for 2 seconds after you stop sprinting and then slower (up to half speed) propotional to how much stamina you have left.
When you get damaged, you are again half as slow for 2 minutes, which stacks with the stamina slow.
When you buy a new weapon, or level a skill you go to the next tier which replaces the three guns/skills. There are 5 tiers of both in total.

I am not telling you how to win. But it shouldn't be too hard to figure out.

Made in C++ using Allegro 5 for the 48h Ludum Dare competition (Ludum Dare 31, theme: Whole game on one screen). This is the Post-Compo version (updated after the deadline)

The Ludum Dare page: http://ludumdare.com/compo/ludum-dare-31/?action=preview&uid=45269

Enjoy!
#shooter