Have Game, Will Play: Aperture Science
Thanks to smealum and lobo from smealum.net/ASDS you can now play a brief homemade version of Portal on the Nintendo DS handheld of your choice, via a homebrew device. There are 14 playable levels and a create mode. Aperture Science DS is based off of the original game’s mechanics. However I can’t tell you where to buy a device to assist with homebrew.