Boats
Unity
Not much of a game yet, but you can run a boat around the sea in impossibly dexterous fashion. Use W and S (or up and down arrows) to move, A and D (or left and right arrows) to turn toward port and starboard. Also use the mouse to look around the world. "Look around" in the literal sense, because there are zero things to look at other than the boat, the sky, and the water. No islands, no skeletons to swash or buckle, and no islands to explore. Good luck winning this one!
If you'd like to download a real program to run on your computer, download links are below the web version, at the bottom of the page. I would be absolutely astonished if your computer didn't complain loudly about running the executable in those zip files. I'm not a certified publisher with Microsoft or Apple, so nothing is signed to avoid those messages.