For this installment of Free Game Friday, I give you …

Title: Psychonauts
Developed by: Double Fine Productions
Published by: Majesco Entertainment
For: Windows
ESRB rating: Teen

This was something of an underappreciated gem when it first came out. Nevertheless, it was a critical favorite in 2005 and has developed a strong cult following since then.

In “Psychonauts” you play as Raz, an oddball kid who infiltrates a psychic training camp and has to learn all he can before his parents arrive to pick him up. He’s a natural at the psychic basics, and much of the game is spend crawling around inside the minds of various characters, each of which reflect their personalities. The art style is intentionally twisted and deformed, and the dialogue is hilarious — much of the game was written by Erik Wolpaw, who wrote the script for last year’s darkly funny “Portal.”

The game isn’t available for free on its own, though you can likely find a used copy pretty cheap online or in a game store. However, it’s free to play through the end of the year on GameTap, a service that allows you to download and play games as long as you do so through the service’s front end.

Most games on the service require a paid GameTap subscription to play (about $10 a month, or $60 for a year), but “Psychonauts” is among a few dozen titles that can be played with a free account. You’ll have to sign up, download and install the GameTap client and game data, and sit through an ad before the game will start up, but aside from the hard drive space and time involved, it costs nothing. But remember, it’s only free through Dec. 31 of this year, so don’t dawdle!

(Image courtesy of Psychonauts.com)