A quick and light "boardless board game" sold by Looney Labs. It's played by arranging and rearranging colorful, stackable plastic pyramids called Icehouse pieces. Here's how:
Each player gets 3 pyramids: 1 Small, 1 Medium & 1 Large. You stack the Medium on top of the Large, and the Small on the Medium. This is your "tree".
In the middle of the table, there's another trio of pieces: a Small standing upright and a Medium and a Large on opposites sides of the Small, lying down and pointing away from each other. This is "the House".
The goal of the game is to arrange your trio of pyramids to match the House.
On your turn, you roll a six-sided die (there's one included in the tube, along with the pyramids & the rules). Each face of the die has a word written on it: "Tip", "Swap", "Hop", "Dig", "Aim" or "Wild". The word indicates the kind of action that you're allowed to take that turn. (For instance, "Tip" allows you to knock over any upright piece or stack and lay it flat.) If you can do this action to your own trio, you must. If not, you may do the action to the House. If you cannot do anything, roll again.
That's it! It's a refreshingly simple game, with a good mix of randomness & strategy. Anyone who's played Looney Labs' flagship card game, Fluxx, will see some similarities. (I tend to describe Treehouse as "like Fluxx in 3D"). I busted out my Treehouse set at Children of the Corny 2 and everyone seemed to enjoy it-- from total nerds like passport & me to more casual players like oakling & ammie.
A single Treehouse set-- 15 pyramids in 5 colors, enough pieces for 4 players-- costs about 10 bucks. Buying a second Treehouse set nets you enough pieces for 9 people to play at once.
But here's where it gets really weird... If you buy three Treehouse sets and a small booklet called "3House", you can then play 3 other, completely different games using the same game pieces: Black Ice, Martian Chess, and Binary Homeworlds.
Pick up 4 or 5 sets, and point a web browser at IcehouseGames.org, and you may quickly find yourself descending down the rabbit hole that is Icehouse, the "open-source board game"-- dozens upon dozens of games that can be played with the same plastic pyramids, some of them very clever indeed... Zendo (a Buddhism-theme mindfuck of inductive logic)... Homeworlds (the game of intergalactic space conquest that fits on a coffee table)... Gnostica (a Catanesque territory game that uses tarot cards as the board)... IceTowers (a bizarre, turnless stacking game)... I could go on and on.
In effect, Treehouse is a fun and simple game that can-- if you're interested-- be expanded into an entire game system, like a deck of playing cards, and used as a springboard for almost anything you can imagine. If that appeals to you, cool. If not, just play the basic game. It's definitely worth the $10 price tag.
Just be careful not to step on them. The pyramids are very pointy and do aggravated damage. Eye-loss is remotely possible. Not for very young kids.