Time travel is a uniquely difficult concept to grapple with in any medium. Time travel in narratives cause problems with continuity, character development, and suspension of disbelief.
Games have, on occasion done time travel very well. Braid and Prince of Persia add time controls to typical platforming, adding a puzzle element to a genre controlled by response time and reflex. Spoiler Alert is a platformer played in reverse, starting at the end and progressing to the beginning.
All of the mechanics I mentioned made play more fun and interesting. With Time Gun, I wanted to play with the idea of doing a time travel mechanic that wasn't fun at all, but was frustrating and difficult to compensate for.
I ended up deciding on a small twin-sticks shooter, where the player was equipped with a "Time Gun", a gun that can send a projectile into any point in time. In theory, this could be used to radically alter the timeline by shooting beams throughough time and into people that maybe deserved to have beams shot through them.
The Time Gun that the player ends up with is stuck on the "random" position, meaning that the bullets fired are shot into random points in the future. From a gameplay perspective, this means the player fires and at a random point in the future the projectile appears and goes off in the direction fired.
This made the game frustrating and hard to play. It also made it hilarious, for myself. I don't know if anyone else found it as funny, the comments led me to believe not. People frustrated about shooting themselve after running into the path of their future bullets was all of the feedback I got. I genuinely enjoyed the project and it still cracks me up when I play it.