4D2 © 1981 Fabris, Robert.
4D2 displays graphic art with machine language for four color panels along with some hidden messages and sound effects. The original programmers concealed the messages so that they would be a surprise to anyone who typed the program into BASIC.
Arcadian 4, no. 1 (November 10, 1981): 5 (original).
Arcadian 6, no. 11 (Oct. 31, 1984): 126 (reprint).