Game Design for my first jam was not pleasant.

I had an initial strategy: Come up with as many games for the theme as I could, flowchart the gameplay loops, pick the best one. Would only take a few hours - and then, the theme was holes.

HOLES???

After making some breakfast (at 3AM, definitely woke up the family), I sat down and got cracking away on some ideas. A Marble Blast clone. A 2D Portal ripoff. A 3D portal ripoff. Katamari Damaci except you're a black hole. Eventually, I settled on an idea:
Action Portal.

The game would be made in Unreal engine and feature a portal gun, as well as traditional weapons, and be a multiplayer FPS. Great - all things I know, besides portals. Hammering away all day at portals until my PC crashed and then jumped into an update loop all night took away my first day, and beforehand, I decided if I couldn't work out a mechanic (in some form) within the first day,  I'd scrap it.

New plan: Black holes. I would use the base for the Action-Portal game I had made, but add black holes to the map and make an ability. In early builds (including some screenshots on here) you can see the wormhole + blackhole ability beside the grappling hooks icon. One problem: The game sucked. It wasn't actually all that fun to play, and it was very easy to absolutely halt all of your momentum with the black hole gun. This was counterintuitive to the rest of the design, and I figured I'd rather lose on theme, than lose on everything else. As such, I cut holes from the game entirely and pounded out patterned enemy AI, really good combat, and expanded on the fun movement. I'd made the tutorial, the weapons (besides the default pistol, which was actually made last!), before sitting back down to consider holes again. My game had no clear, consistent strand of design holding together the conceptualized levels, and it featured two modes at this time - Arena, and Gauntlet. I slashed 3 weapons - the lightning gun (quake style beam), the plasma rifle (full-auto energy weapon), and the black-hole grenade in order to focus the weaponry down to a more modern style (and for consistency between 3D model assets on that front). I realized wormholes could be a plot element and added them in as the enemy spawners, level ends, level starts, and overall plotline, and slashed Arena in favor of Zombies.

It was Day 5 out of 7, and I was only then realizing what I wanted to do with the game I had made. Fantastic.

I quickly got to work on maps, although I had to reduce the map count from 5 to 3. Zombies mode proved easy to implement, but building would take all of Friday night and I didn't have time to test in case of needing to re-package the game for bugs, so I had to cut it. I'll be patching it in for free since a lot of the work on it is already done, once the rating period and all that ends and we're allowed to do so. In the end, the game turned out far shorter than I wanted it to be, but the gameplay is fun enough to make up for it.

Happy jamming folks! I learned a lot and really enjoyed this.