Arrghhh. I deleted my comment on accident. Here's what it said in short:
presentation- good,
shooting- fun
gun- reminds me of quake
difficulty- too low, could ramp up faster. Every time I got killed it was because I got bored, because no enemies were coming, and wandered to look for green orbs.
Over all- pretty good game, and so far only FPS in this jam! Cool!