Available at: Assault Publishing
Assault Publishing has released a free expansion and demo ruleset for their PMC 2640 Ruleset. The Main ruleset is very well written and I'd recommend everyone downloads the demo and checks it out for themselves.
From the release:
Today, I am pleased to release PMC 2640: Hell on Echidna, a free demo version of the PMC 2640 wargame! However, it is not only a demo, but additionally a mini-expansion, which features several new, cool rules for those of you who have already purchased the book.Hell on Echidna is not the typical bunch of a few random pages. It contains all the basic things you need to play: core rules (identical to those found in the rulebook), a shortened terrain list, a special, new terrain generator for post-apocalyptic planets, rules for composing an army with basic equipment, a wholly new scenario (not featured in the main rulebook), and a list of several units (including two new ones!) and all their special rules. Additionally, I have included a new Battle Honour, which may be given to your troops if you decide to play your campaign battles on Echidna or a similar devastated planet.
To summarize, Hell on Echidna gives you everything you need to get to know the game's mechanics, theme and design philosophy, and, of course spend a great time playing it! But remember that it's just a small part of what you can find in the full version!