Gearhead: Arena and Gearhead 2 are mecha piloting roguelikes with procedurally generated plots, created by Joseph Hewitt.

Gearhead takes the common elements of roguelikes and builds a more conventional RPG with them while keeping the procedurally generated aspects. It features procedurally generated maps, characters, sieges, plots, quests, and conversations.

The player is randomly assigned one of several possible background stories at the start of the game, and the overarching plot is derived from the exploration of the modular plot points that result from that.

The core procedural generation system in the game uses a template-based  language that lets a designer define maps, quest events, character dialog, and so on. Many plots also spawn rumors that let the NPCs refer to them during the procedurally generated conversations.

While Gearhead 1 is a finished game, Gearhead 2 is a little bit rougher, with development stalling after a switch from Pascal to Python. But it does have a bunch of new features and a solar-system spanning procedurally generated plot that’s designed to finish in a climactic battle against a recurring antagonist.

The Gearhead website appears to be down right now, but since the games are open source, they can be downloaded from SourceForge. Both games have an ASCII version and an SDL graphics version; if you download the SDL version of Gearhead 1 you’ll also need to download the images in a separate package.

http://sourceforge.net/projects/gearhead/
http://sourceforge.net/projects/gearhead2/