As I went through the Steam sale and saw a game for 14 cents I couldn't pass it up, as at first glance Caster looked like a Megaman/Sonic hybrid but let me assure you it captured not a single element of what made those games good.
Caster is a mediocre shooter that does not contain any good qualities. The objective in each level is to either kill every enemy or do a boring fetch quest, there are a few other missions with different objectives that are just as uninteresting, for example; shoot a tree. Every level is incredibly short, each one averaged no longer than a minute and the total game length isn't much longer than an hour.
The game abruptly ends with a "To Be Continued...", and despite being released in 2009, there has been no continuation. Enemies are all very generic, and each one of their attacks can be easily avoided by just sprinting around or jumping. Even if they do manage to hit you, they deal hardly any damage, and they are easily dispatched.
The story is uninspired, and unless you've never heard or seen the "It's humans against aliens, you're our only hope!" plot, then I doubt you'll be interested. I did not find Caster to be particularly interesting in any way.
Terrain destruction and super speed can be fun and worth it if you paid the 14 cents sale price but only for about fifteen minutes, so if we do the math less than a cent a minute is decent but beyond that, there's not much else that the game offers..
It's definitely not worth the actual price of $3.29. In closing I would give Caster 2 soggy marshmallows out of a possible 13.5