I have played through this game three times since its earlier days, and I can never get enough of it. I even paid for it twice; 5 bucks for this much fun is just a steal.
What is Zigfrak? Pure unadulterated hilarity in the shape of a space shooter. I mean, it's got "loot piñatas" right in the description.
To say it's got a quirky humour doesn't do it justice; battles are a flashy, dopamine-torrent-inducing show of lights and loot. There is a joke to be found absolutely everywhere, from the purposefully shameless stereotyping (often with a twist!) on some of the characters, missions, and dialogue, to the very names and flavour text of the majority of the equipment you can find: when you get your hands on a nuclear missile launcher called The Freshmaker (with "plutonium cores enhanced with minty flavour crystals") you know this game's a keeper.
It's not a "hard" or "challenging" game by any means. While you are certainly able to roam in-between missions and find yourself in the middle of a bigger badder fleet than you can manage, once you get the hang of the mechanics and controls the answer is most often just getting a few more levels and better gear. The game is pretty streamlined for the sake of fun; and it succeeds, because the humour, the story constantly switching mood from dark to kickass to zany, and the flashy battles WILL keep you entertained for dozens upon dozens of hours.
From a technical aspect, the graphics are not the most realistic hi-poly thing you'll find but it's nevertheless got a unique and beautiful style. The soundtrack is great, and the game is extremely stable and bug-free.
What doesn't it have? Multiplayer, or a truly unforgiving challenge. If you don't really need either of these, then Zigfrak is your game.