Fhourstones is an integer benchmark that efficiently solves positions in the game of
Connect-4

Connect Four

Connect Four is a two-player game in which the players first choose a color and then take turns dropping their colored discs from the top into a seven-column, six-row vertically-suspended grid...

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Available in both ANSI-C and Java, it is quite portable and compact (under 500 lines of source), and uses 50Mb of memory.
The benchmark involves (after warming up on 3 easier positions) solving the entire game, which takes about ten minutes on contemporary PCs.

Fhourstones was named as a pun on Dhrystone

Dhrystone

Dhrystone is a synthetic computing benchmark program developed in 1984 by Reinhold P. Weicker intended to be representative of system programming. The Dhrystone grew to become representative of general processor performance...

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(dhry sounds exactly like drei, German for three, so fhourstones is like dhrystone++)