There are 5 different missiles you can buy (or earn as bonuses). As you 
can probably guess, they increase in price and damage factors. 
NOTE: The prices I’m listing are different that the prices in the screen 
shot. They are:

- Straight – Cost = $120 – This fires two missiles in a straight trajectory 
  so you need to be lined up with your target. 
- Smart – Cost = $400 – The Smart Missile seeks out the enemy target on 
  it’s own 
- Medusa – Cost = $750 (approx) – Bigger missile causes bigger damage. 
- Swarm – Cost = $1200 – The name says it all. This unleashes a swarm of 
  short-range missiles that do heavy damage 
- Nuke – Cost = $2400 – This is the Big Kahuna! These are expensive so save 
  ‘em for the bosses.