There's no doubt that I've probably missed other attempts at re-conceptualizing Valve's seminal FPS puzzler Portal in to a top down puzzler, but Portaball by Bartosz Ciechanowski is one of the first I've come across and as mind-benders go it doesn't hold back on the challenge.

You'll be slowly introduced to new objects over 50 currently available levels that will change the behavior of a frictionless ball as it bounces around the puzzle environment. Certain specific walls can have one of two different portals opened on them and you'll need to manipulate them in order to navigate around the level to make it to the exit. Barriers, switches, 'phasing', speed pads and holes all combine to confuse and distract players from the often elegant solution required to complete the level.

The visuals keep the Portal-esque theme rolling with its clean mono-tone style, however the designs are clear and easy to read, making even complicated puzzles easy to follow once in motion. Portals can be shifted while the game is paused and the developer encourages players to use this feature to solve time sensitive puzzles. However a bug currently affects when players can pause as holes will continue to open up and cause your ball to fall even when time is stopped.

Challenge modes attempt to extend the life of Portaball, though once completed only leaderboard junkies will really keep plugging away and it would be good to know if more content is planned. Still, if you enjoy a stiff challenge and don't mind the occasional puzzle stumping you then Portaball's elegant gameplay is well worth checking out.