We now have the following versions: Top of the line: Chess King 4 for PC, Chess King 4 Pro for PC, Chess King 4 for Mac. These versions include the top engine Houdini 4. For the PC we have versions with previous generations of Houdini at reduced prices, but with the same interface: Chess King 2 for PC and Chess King 3 for PC All have also the GigaKing database and opening tree, etc. All work with all versions of Windows incl. 8 and all are multilingual.

The ONLY difference is the engine Houdini 2 vs. Houdini 3 and Houdini 4.

Houdini 3 and 3 Pro can play Chess960 (Houdini 2 cannot due to the complex castling rules)

Houdini 2 is a 1-processor engine, rated around 3200 (still stronger than all humans) Houdini 3 supports up to 6 cores and is rated about 3300 (a tiny bit faster since uses all cores) Houdini 4 supports up to 6 cores and is rated about 3400 (a tiny bit faster since uses all cores) Houdini 4 Pro supports up to 32 cores, but you need a super PC for that.