Wow, over 700 people have downloaded that 413 game Tang and I made in 9 hours. Wowie!
It sounds like the file just is not supported by newer macs, which is very surprising to me, but possibly not fixable. You could run it through a program like Sheep Shaver, which will emulate older macs, but if you do so please be extremely cautious because I have not thoroughly looked into it.
You may be better off downloading the PC version and running it through WineBottler, a program which can run most simple .exe files on macs. The site I linked explains how fairly simply.
Happy 413! A tiny bit late for my timezone but w/e!
Here is a fun, 9 hour, Homestuck game to play! I coded it and Tang made most of the sprites! Kill all the enemies and defeat the boss! Arrow keys to move, Shift to attack, Z to special attack, 1-4 to change characters!
The end of an exciting saga!