Delta 4 was a British software developer founded by Fergus McNeill, writing and publishing interactive fiction.
Some were self-published, others were released by CRL Group, Piranha Software, Silversoft, or On-Line Entertainment.
Psycho Killer is a graphic action-adventure game released by On-Line Entertainment in 1992 for the Commodore CDTV.
[6][7] Gameplay of Psycho Killer is restricted to a point-and-click interface, such as clicking certain arrows to go their respective direction.
[6][7] In issue 32 of Amiga Format, the reviewer gave the game 13% and complained of "poor gameplay",[6] comparing it to an "interactive home movie" and asked who would want to play a game featuring a "spotty herbert who drives a Vauxhall Chevette".