
Since we used Gitlab CI to automatically build our game on each git push, we have easy access to bunch of builds of earlier versions
of the game online.
EDIT: Apparently Gitlab CI artifacts expire after 30 days, so all of the links in this post are dead. Oh, well..
I thought it would be fun to post some links to earlier versions, so you can see how our game came along.
Earliest build I have
Commit ea57884d - Saturday at 3PM
Click here to play it
We had the top scanner bar working, but it doesn't display any inputs.
All the graphics are the godot logo. We were going for an orange UI at the time. Movement was continuous, and not on a grid. There are no bounds, and larger screens just get a larger visible area.

Decide to play on a grid
Commit 873067c6 - Saturday at 6PM
Click here to play it
We decide to make the movement grid-based, to make the loops more predictable. Back when they were continuous, it was impossible to avoid drifting (a lot) on each loop. It was also hard to visualize the movments in the top bar.
We made the background dark. We changed controls to have movement on WASD, and shooting on Arrow keys. There was some discussion about this - and some players have commented on this after release. (We should probably make this configurable, post-jam).

Needs More Glow!
Commit 20e4b744 - Sunday at 4PM
Click here to play it
We have a (temporary) start screen and a game over screen now. If you've played the final game, you'll know that the game over screen didn't end up being so temporary. Very typical...
We removed the Godot logo sprites and added a big bad glow effect. We made the bar in the top larger, and made the background completely black. We put stuff on a centered, bounded grid (but it's still invisible).
This game plays more or less like the final version. The most notatble differences in mechanics here are that bullets can shoot bullets, enemies killing enemies gives you points, and the spawning logic is a bit different.

Juice it up
Commit 1d4adc3c - Sunday at 10PM
Click here to play it
We add a grid to the background, make the top scanner bar pretty. There are now particle effects when killing enemies. It's beginning to look similar to the final version.
This game still has way different strategies than the final game. If you spam enough shots, you can practically become invincible. A playtesting friend managed to get thousands of points in this version.

Polish, Polish, Polish
Commit 75406e0a - Monday at 6PM
Click here to play it
The main character now interpolates between grids when moving, instead of just instantly blinking over.
We added controls to the background. We added a highscore screen. There are now particle effects when the bullets hit the walls, and screenshake when killing an enemy. The shots are colored according to who shoots them.
In terms of gameplay, we added the ability to melee-kill opponents, and we added the miss-bonus so prevent players from wanting to fill all squares with bullets. We added the restriction of shooting only once per round, and we added the +10 point clear bonus to incentivize players to get out there and shoot stuff, instead of just dodging bullets.
The game still doesn't have a theme at this point.

Final edition: Slap theme and name on it in the very last moment
Commit 4763b71d - Monday at 11:40PM
Click here to play
We were having a really hard time coming up with names. Loopy Boi? Cyberspace Timeloop? They all kind of sucked.
We decided of forcing the game into a more concrete setting, instead of trying to find a name for the abstract game we made. Once the name "Timeslime" was suggested, we commited hard and started making the main character look like a slime. We added the particle effect slime trail behind it, we made it more green and rounded the corners, and we made it stretch a little bit when it moves. Then we hurriedly made a cover image in Aseprite and slapped a logo on it.
This is the game we submitted for LD51.

Sorry if this was a bit much of a wall of text - I hope someone out there enjoyed stepping through the process with me :3
Let me know what you think! How was your process similar or different?