Trench

Each player starts with a shuffled stack of all cards from one suit (or two for a longer game). Players deal cards face-down into their own rows of front and back "trenches". A player may peek at his own cards anytime.

A turn consists of one of three actions:

Reveal a card in the opponent's trenches.
Swap positions of two neighboring allied cards.
Attack: Flip two directly opposing cards. Discard the weaker card, and return the stronger card to the owning player. Each player slides a card from their back trench into the spot emptied by the attack and lays a replacement card in the back trench.

A player left with only three cards loses.