Secret Rooms : to get to a secret room, perform a secret trick on a level. Some of the secret tricks are :
1) Teleporting into the exit.
2) Pushing a movable wall into the exit
3) Keeping all the super shots
4) Not using invulnerability (this is almost always a good idea anyway)
5) Not touching a fake exit
6) Teleporting on top of Death and/or acid blobs
7) Not taking ANYTHING (the tick trick comes in handy here)
The hints it gives to the secret room don't necessarily apply to your current level, just as on "Gauntlet". The secret trick usually doesn't work, but it is always same for any given board. You're allowed one secret trick for every 15 levels or so.
You can kill the acid blobs! Just drop 2 potions in quick succession. This works regardless of your magic ability. It also puts the dragon back to sleep momentarily (You can also kill them with a teleporter...if there's a teleporter handy, that is).
The '?' foods are NOT random. Grab a '?' food on health mod 20 = 7 (i.e. 27, 47, 67, etc). You'll get 200 health.
Couple of strategy notes :
1) Reflective shots make the dragon easier
2) Invulnerability makes him very easy
3) Remember that when generators aren't on the screen, they don't generate monsters.
4) If you are playing two+ player you can kill almost all dragons with one player diverting his attention, or using an indirect attack. For example : you can find shootable walls or just stand in the right spot askew from the dragon. He will try to flame instead of fire-ball. If done correctly, you will be standing a wall away from him. Then your partner can go around and shoot flame head while the dragon is flaming away.
If a previous game ended beyond Level 6, Level 6 in the next game becomes the level that the previous game ended on. If you got a really good sequence of boards in a game and you want to repeat them, turn the machine off and on again after you've entered your high score.