Color me intrigued.
http://mightyatom.blogspot.com/search/label/regiment
Alpha versions are free. It presumes some familiarity with games Powered by the Apocalypse, so if you're not already playing AW or DW there's probably not quite enough in the text to make a game out of. If you get the Dungeon World book (free) or Apocalypse World book ($10) then you can fill in the details.
I have yet to play this, but I am grooving on the ideas presented herein. I like the focus on combat, class balance, attempts to render complex tactical situations through relatively simple mechanics, and setting.
I find almost all pen-and-paper roleplayers really like combat while a smaller fraction of them enjoy the non-combat aspects. As a marine, your responsibilities as a PC are entirely about combat.
The Regiment has all character classes dealing equal damage. I have seen motions towards this level of equality, particularly in Edge of the Empire, but even there the system is set up so certain classes have advantages when it comes to dealing damage. The Regiment is perfectly flat when it comes to expected outcome across classes on dealing damage given a particular weapon, and the starting weapon selections are similarly flat (only Synthetic does not have a 3d starting option). The separation of the character classes in The Regiment has to do with how the characters deal with bad shit, apart from blowing it apart.
The Regiment isn't a war game. I find almost all the pen-and-paper roleplayers I know dislike the thick rulebooks and tedious rule applications of war games. A moiety of RPGers are into the beer+violence but don't really pay attention to the rules, relying on other players' rules knowledge. These kinds of players make suboptimal decisions when playing war games, which leads to disillusionment with the system and dissatisfaction of their opponents and allies.
I really like space marines, as a genre. This type of setting provides a good balance between grittiness and heroism. I want to play & like Apocalypse World, for example, but the messiness of the setting impinges on my anticipation for the game. I also like heroic fantasy, of course, but a certain kind of space combat is also right up my alley. I find one problem I have with Edge of the Empire is the seedy hives of scum and villainy backdrop our characters inhabit and the limited options we have for being heroic.
The Regiment seems like a fine blend of combat-heavy PnP RPG in space, and I am excited to try it. Trying to convince one of my regular groups to give this a go.
The PDF playset includes a starting adventure with a bunch of GM specific info. If you want to be surprised as a player, don't read the GM sections or maps.