What did you do for a Tarrasque adventure?
When you ran it, did you wait for the players to be epic level?
Did having such an overpowered enemy detract from anything?
Or did your players - on the contrary - find it too easy?
All together, how did you make it work.. did the Tarrasque fall out of the sky and that was that or was it part of a long-winded, many-year game, finally culminating in a session you titled The Call of the Cthulhu Tarrasque?
The Tarrasque is not a monster to kill. It's a problem to solve by other means. We had to deal with the Tarrasque once, but we never actually saw him, we just know it was coming and had to migrate a whole population. We went back to find a completely obliterated country.
When you ran it, did you wait for the players to be epic level?
We were high level (around 18th), but not epic.
Did having such an overpowered enemy detract from anything?
No, it's just a different challenge. You can build an intriguing backstory on why he was awoken, or what are the consequences (political and economical) of his appearance.
Or did your players - on the contrary - find it too easy?
All together, how did you make it work.. did the Tarasque fall out of the sky
It sort of appeared out of nowhere, but we knew it was coming, and was part of a much longer and complex campaign.
and that was that or was it part of a long-winded, many-year game, finally culminating in a session you titled The Call of the Cthulu Tarasque?
It was in the middle of a 18 months "part of campaign". Our campaigns are all intertwined and last years. I have friends who are still playing characters, children of characters and settings we started in the year 2000.
http://forum.rpg.net/showthread.php?t=261519
It describes a city built around a imprisoned Tarrasque and all the strangeness that comes from having that at the heart of your city. Like Stefano said, the Tarasque is better as a plot element in the background than simply a monster to fight.
I've only faced a Tarasque once and that was in the low 10's of 3.5E D&D. Our goal wasn't to defeat the Tarasque, but to slow it down and ultimately get it to change course so that it wouldn't reach a major city.
In general, you can use an overpowering enemy like this to force them to deal with things a bit more creatively than simply trying to kill it.
I once wanted to run a game where the players were visiting a city built around a kind of stonehenge of smooth orange obelisks.
The entire island would eventually turn out to be the Tarasque's back when the monster awakens, turning the city on its side and leaving the players in an "escape-the-city" scenario.
This is a very awesome boy, so treat him appropriately! I'd give you two options: 1) You encounter a Tarasque at a mid-high level and you have to deal with him "creatively", but not kill him, and continue the adventure. If you try and get the Tarasque head-on, you'll be easily destroyed, as the adventure is all about avoiding frontal fight. 2) At very high level (epic), on the path to Immortality, you encounter (probably one-to-one) a Tarasque, and this time you have to destroy him. Enjoy!