Speed is POWER. But speed is also DEATH. Gain power, gain speed, gain death. Alex Bethke's Starfall, created for the most recent Experimental Gameplay Project contest (theme: High Velocity) is as simple as a videogame can be, and that is exactly why you'll be playing it for hours.
Collect the glowing orbs to increase your score, but suffer an associated boost to your speed - during which you will struggle to avoid the nasty red orbs. Well, you won't, you awful show-off, but the rest of us will be cursing the rush of deadly, precious speed.
Ever so simple, ever so thrilling and ever so tense: it's like drunk driving without the absolute, indefensible idiocy.
Thanks to Michael Cook for the tip.