Aspyr has released a demo version of its first person shoot-em-up Return To Castle Wolfenstein.

The Mac conversion was released earlier this year. The 108MB downloadable demo offers two single-player levels.

In the game, players become B J Blazkowicz, a secret agent sent deep into Nazi-held territory to put a stop to a sinister occult plot by SS leader Heinrich Himmler.

Himmler is abusing technology and mysticism in an attempt to create a super race of soldiers – if he succeeds, the Allied armies will lose the war.

The game requires a PowerPC G3 500MHz or better Mac, with 128MB RAM running Mac OS 9.x or Mac OS X 10.1. An ATI Radeon or NVidia GeForce2 MX graphics card is also necessary.