Love some retro action-platformer to fill your time? Janosik quite a popular one, likely because it's free, and it just got a big upgrade.
"Janosik's companions were captured by the evil Count Von Zur and it’s up to you to find and rescue them from the prison. Explore hand-drawn pixel art world, find secrets, jump over deadly obstacles, roll and attack enemies, collect gold coins and find upgrades. Janosik gives you about 2 hours of single-player retro platforming fun."
The developer is currently working on a full sequel, and they decided to come back and improve the original. It moves to the latest Construct game engine along with adding in a map, travel corridors to connect up parts of the game, a new NPC that sells sword upgrades, lots of levels were re-designed, various new enemies, lava, new levels, new boss mechanics and much more.
Sounds like a rather great upgrade for a free game.