Image from Grey Knights Codex
With the April issue of White Dwarf containing a few new rules for games on Death Worlds (24 alternative rules and 3 new scenarios), I thought I might expand on that and provide a few more rules you all can use in your games to add some variety to the normal game of 40k.
Hazardous Environment chart
The first thing is a huge set of hazardous environments (66 of them!) This is not mine, it came from GW a long time ago and all I did was translate it into a document my old gaming group could reference and use. Fair warning, these are not "fair" and may tilt the game one way or another. That being said, they are a ton of fun to use.
Download the Hazardous Environments PDF here
Image from Games Workshop
Daemon Worlds Rules
The next set of environments comes from an older issue of White Dwarf. These cover Daemon Worlds and I thought these would have seen a bit more exposure when the Grey Knights came out, but they didn't. While not as in-depth as the Hazardous Environment charts above, they can add some flavor to your game especially if you play Daemons. Even if you don't, they can still make things interesting.
Download the White Dwarf Daemon Worlds PDF here
Image from Games Workshop
Jungle Fighting Rules
And last but not least is one more set of rules to help out. These come from the old Catachans Codex and outline some dense jungle fighting situations. As if true line of sight isn't enough of a problem these days.
Download the Jungle Fighting rules here
Use at your own risk
UPDATE: Here is the White Dwarf Cities of Death supplement that was mentioned in the comments. It has a few more strategems and a handful of new scenarios as well. Enjoy!
Download the WD Cities of Death PDF here
Make sure to check out these posts as they might help:
The social contract we agree to when playing 40k
There is no "auto-tie" mission already!