 The company's first software release was a compilation of games for the Sinclair ZX81, though it was with the ZX Spectrum that Crystal found its greatest success.A deal with the machine's manufacturer Sinclair to distribute Crystal's "Zeus Assembler" gave the company sufficient funds for a major marketing campaign for their next product, "Halls of the Things", an arcade adventure game that became their most successful title.Clarke left in 1984 to join Artic Software, where he worked on the "business side", before collaborating with Jon Ritman on the "Match Day" series.