7/10 If your a fan of WH40k and you can get this cheap (I was able to get it around $8), then there's no reason not to get it.
The main draw of this game is to see the Warhammer 40000 universe in the flesh. The Dawn of War series was an excellent way to portray the universe supplying plenty of flavor and the kind of combat one would expect. However, the world still lacked the scale and grandeur one expects from a culture engrossed with the gothic style of art and a universe where there is only war.
This is not a problem with Space Marine as straight from the get go your thrown into a world literally at war. The world you fight on is a forge world under siege by the green menace, the iconic orks. A world where every resource, be it natural or otherwise, is dedicated to the manufacture of weapons and materials to feed the war engine of the Imperium in its everlasting war against the enemies of mankind.
You play as a Space Marine, a genetically enhanced post human angel of death. Arguably the Imperiums greatest weapons of war. So mighty, often a single squad is enough to pacify an entire world. So rare, it is said that there is but one space marine for every world in the imperium.
You know what the biggest issue I have with this game? It's that barely any of this is explained to the player. You would think that for everything a player sees and experiences he would get a little information to provide context and information. Does a stranger to WH40k know what is a forge world, a space marine, the imperial guard, chaos, the warp, psykers, titans, bolters, the Emperor himself etc, etc. I'm particular annoyed that not once in the entire game did I see someone say "The Emperor protects". An entire universe of lore and barely any of it is expressed.
What little there is however, is really impressive and gratifying to see. On to the details of the game.
Very short game. Approximately 6 hours on the hardest difficulty depending on how adventurous your feeling during the fights. Though for the type of game this is, adequate enough. Because of it's length the repetition of gameplay doesn't hit you nearly as much as it could've. Haven't tried the multiplayer as I wasn't expecting much from it.
Impressive not because it looks good, even though it does, but because it does what virtually no other warhammer game has for me. It brings the WH40k universe to life. The armor the space marines wear still has that blocky feel one would expect, but the armor has a sense of antiquity, rigidity, and beauty to it that is always hinted at in the books and artwork. The manufactorum fills the screen with it's grandeur despite it's distance to the player. The titan towers the way a machine god on the battlefield should. Everywhere you go everything is made in such a large scale that befits the style. That being said, the world itself is very uninteractable with the player being able to "touch" very little.
The combat is solid enough. It fits the tone being brutal and visceral in ways that it should be. It gets repetitive pretty quickly in that there are only 1-2 kill animations per melee weapon, but it scales things in such a way that your still getting something slightly new throughout the game mostly in the way of new weapons.
The music is somewhat bland despite it fitting the game, there just wasn't anything particularly "epic" about it. Everything sounds the way one would expect it to from the impacts of the melee hits to the discharge of the range weaponry.
7/10 Again, if your a fan of the WH40k universe there's a lot of little things that will be fun to see. Get it if its cheap as it's a treat for any fan.
For the strangers you'll be missing a great deal of the lore in this game with no context to help you understand this grim universe. In all likelihood it'll just be another small action game to you which you'll forget about.