Game Rules
You can of course just use your scaled up models as exactly what they represent in whatever codex you use and most players will be fine with you using slightly larger models and even slightly larger bases (I for instance you 30mm bases instead of 25mm).
But for those of us who love accurately scaled Space Marines there are many who want their cool and unique models to play in their games in the same way they are represented in the background fiction and fluff. Here are some ways in which to do just that.
1. My personal preference is to use GW’s official codices to create legal Space Marine forces where models in power armour are represented within the rules by Terminators or their equivalent. Here’s a few options, none of which are likely to be very competitive on the table (but that’s OK):
- a) Pure Deathwing force. Model’s power armour counts as terminator armour, bolters count as storm bolters, heavy flamers count as flamers, so on and so forth. The problem with this is equipment like power fists don’t make sense as there aren’t many power armoured squads with more than one powerfist in it.
- b) The new favourite is the Space Wolf Wolfguard list. When led by Logan Grimnar, Wolfguard can be taken as troops choices and they can also all be equipped with Terminator Armour. This list is probably the most flexible for equipping each model with accurate “counts as” weapons. Might work well for smaller games.
- c) Grey Knight Terminators. Because all Grey Knights carry the same weapons regardless of armour they wear, using GK Terminators rules to represent GKs in Power Armour is pretty straightforward. Add to this the fact that they can be allied into other Imperial armies makes this a great way of adding giant Marines into your Guard or Inquisitorial forces. This is my favourite way of fielding Actual Scale Marines where their models really stand out amongst a force of lowly humans. You can use the GK Terminator rules to also represent Space Marines from other chapters carrying a power weapon and bolter (veterans for example) and therefore use a squad of correctly scaled Ultramarines (or whatever chapter) with your Guard army.
- d) The Scout heavy force. Using the Space Marine codex with Scouts forming the bulk of your force and as many Terminators as you can afford, represented in game by your scaled up Marines in Power Armour. The good thing about this is aesthetically the Power Armoured Marines stand out because they tower over their younger battle brothers, and you also have less conversions to do to field a full army (also Scouts have some pretty cool options). I’d really like to someday make a Scout heavy force like this for either the Lamenters or Scythes of the Emperor chapters, just because it’s fluffy.
2. Another option would be to play your games using the “semi-official” Movie Marines rules published in the US version of White Dwarf a few years back. These are of course just for fun rather than competitive play, but surely fun should be the priority. You can find the Move Marine rules here: http://www.belloflostsouls.net/2009/12/40k-playtest-movie-marines-in-5e.html
3. Finally you can create your own rules. Included here are two PDF documents created by AJ Twombly. Please feel free to try out these rules and give AJ some feedback (email him at mastercraftedmodeling@gmail.com ).