I was wrong! I looked it up and here is what wikopedia says anyway.
Aside from the common-sense rules (no biting, no eye-gouging, etc) the rules were pretty much as follows:
* No elbows to the head (neither standing nor on the ground).
* No closed-fist strikes to the head (neither standing nor on the ground).
* No knees to the head on the ground.
* No kicks/stomps to the head on the ground.
* If you get too close to the ropes, you are stood back up on the feet as opposed to PRIDE's recentering in the middle of the ring.
* Non-title matches=One 15 minute round; Title matches=One 30 minute round.
* If you are caught in a submission and you tap out (whether you can't reach the ropes or the submission is just too tight) you lose.
* Five "escapes" are given to each fighter at the start of every match. An escape can be used if you are caught in a submission near the ropes, in which case you can grab them and you will be stood back up on your feet and will have one point deducted. Once you have used all of your escapes, you lose.
* For knockdowns, a ten-count similar to boxing and kickboxing is used. If the fighter is unable to answer the ten-count, it is declared a TKO and that fighter has lost the fight. However, if the fighter is able to answer the ten-count, the fight resumes and one point is deducted from them the same way it would be if they were to have grabbed the ropes while in a submission.
* If at the end of regulation neither fighter has been knocked out, submitted, or lost all their points, a decision is rendered based on who lost less points (which is what it means on the fight finder when it says "Decision (Lost Points).") If neither fighter lost any points or they both lost the same number of points, the fight is declared a draw.
* In the 1994 King of Pancrase tournament, the rules were slightly different in that the first round had one 10 minute round and three rope escapes and the finals had one 20 minute round with three rope escapes.
* In the King of Pancrase tournament final, even though neither fighter lost any points at the end of regulation, because it was a championship match, they didn't want it to be a draw so they rendered a decision anyway.
* And one other sidenote: For a short period of time around when Bas was the King of Pancrase, heelhooks were banned because of the frequency of injuries.
Today, Pancrase uses mixed martial arts rules similar to the ones in PRIDE FC and Shooto.