KEMPELEN by Sierra Online first came out in 1986. The programm which was written by Atilla Kovacs is suitable for beginners and casual players.
There are 10 Levels which can be changed holding down the TAB key on your PC and pressing a number key. TAB + P forces KEMPELEN to play the next move. TAB + N starts a New Game. Other options are also available by holding down the TAB key and pressing letters on your keyboard.
The playing strength of KEMPELEN is approximately 1150-1250 ELO (1350 - 1450 USCF).