I played this through in its entirety back when it got released way back when. Found it randomly on GoG. Played it again, still awesome. Then I noticed GoG included the original as a bonus download, how great is that?! Classic twin stick shooter. The enemy patterns are predictable, making games deterministic. When you hit kill milestones, you get perks, which are semirandomised, which adds a degree of strategy, and only serves to make the game more awesome. Levels usually last under a minute unless you're doing crazy survival runs. And the story is great: here's guns, go shoot zombies/spiders/aliens. 5/5 because the remake stands up after, what? 17-18 years? By the way, if you've played this when it came out, it came out in 2003. Let that sink in for a moment.