When I was in High School, my mom took me to Washington DC's Eastern Market. There, I met a vendor who had an interesting game. It was played on a 4x4 checkered grid, with each player taking control of 4 pieces. Each turn, a player could move one piece one square, just like a King in Chess. However, you could only take pieces by jumping over them, like in Checkers. To win, you had to eliminate all of your opponent's pieces. Or, you could get all of your surviving pieces to the other player's home row. This rule meant that you could have one piece left, but if it was at your opponent's side, you won. Despite the simple ruleset, the game is surprisingly deep and interesting. The vendor called it "Peruvian Chess", but I haven't been able to locate anything else under that name.
So, mostly as an exercise for myself, I've been making a digital version of this game that no one else has ever played. Partially because I'd like to introduce it to other people, and carrying the board around is a little too inconvenient/obsessive. But also, I plan to write an AI to play the game, so I can actually have an opponent when no one else is around. Eventually, I'd like to give it an online component, but it's nowhere near that level yet.
Currently, it only has two-player hotseat mode.