I'm on the island. The "stone" flew away and I went down the hole.

But, even with the green stuff that lets me run faster, I can't get past the long row of vents. Almost, but never quite get there. It's getting old .. I've tried to time it with the lights and steam. No luck.

I also put weights on the white spots in the first room and the room with the hall of steam vents. No difference.. Am I missing something?

It's a timing puzzle, running over the vents blindly gets you teleported back. You need to observe the pattern of the vents, and try to time your walking over them to get you past without touching any of the steam. The last one may be a bit tricky, since you have to wait a bit while actually standing on the vents in the middle.

If you still find it difficult, you can always cheat. :)

I was desperate enough to try cheating, but they don't seem to work with my GOG version.

thanks....

The cheats work with every version, but they may be a bit difficult to activate. Be sure to hold SHIFT+F1 first to activate them.