Secret levels in Saturn Quake!

I have completed Saturn Quake totally (Shub-Niggurath is down!) and on the way I stumbled upon a secret level, where you choosed a monster and it battled against a monster chosen by the computer in an arena. (pretty cool, pokemon crossed with quake :) ) I have heard that there is three more secret levels. Anyone who knows where they are? Please help, I would love to finish this game completely :)
Gamefaqs has a list on which levels the secret exits are, but not where on those levels. I have found another secret level though : The one in the first episode. A really cool level with loads of pretty flickering fires and nice arcitecture. Lobotomy really showed off here...
there are three in total I think.

one is before or after the Hells Antrium(inside the right window with the virtaux).

The levels are

Quake Arena(the one you got into)

One level with High jumps

and a Suppa-Duppa rolling comic with the 2 main characters giving the creeps on some poor monsters(this one is the one I wrote above I think)

ummmmm... :damn:

I don't remember much cause the last time I played the game was before 4 years.