No turns at all. Both players empty their hands at once.
A two-player game with no turns at all. Both players play simultaneously, as fast as they can, and it is over in a minute.
A 52-card deck split in half, 26 cards each. From your half:
Deal five cards to your hand. Place fifteen face down as your draw pile. Put the remaining six face down as a side stack.
The two side stacks go in the middle, and one card from each is turned face up between them.
There are no turns. Both players play at once onto the two central piles.
A card may be played on a central pile if it is one rank above or below the top card. On a nine you may play an eight or a ten. Aces are both above kings and below twos, so the sequence wraps around.
After each card you play, draw from your pile to bring your hand back to five.
If both players are stuck — neither can play and neither can draw a fifth card — each turns up one card from the side stacks onto the central piles, and play resumes.
If the side stacks are exhausted, the central piles are shuffled and split again.
The first player to get rid of their hand and draw pile wins. Best of three or five is normal, because a single game takes almost no time at all.