Hey there, here is something you gotta keep in mind:

1) add music .... gives the game a lot more flair
2) Weapon-specific Skills.... give each Gun a specific special skill..... sniper deal more damage the more far you away..... Shotgun can hit multiple times ..... and so on
3) Dashing multiple times would be nice
4) Some "Reload" Points would be nice where you can charge up to dash faster or charge your special ability