Additional information from the coder József Punk:
"Stalker is a prototype of an Amiga game I developed with two of my friends about 20 years ago. The main unique feature of the game was the rearrangeable playfield. The player controls a two leg robot in a scene that is built by same sized blocks. These blocks are moveable in rearrange mode. It was totally written in 68k ASM in AsmOne. The target spec for Stalker was an Amiga 500 expanded to 1 MB RAM (chip or fast)."