Yes I am making this kind of game with a friend.
Like you choose race and after that you can choose to develope yourself when finishing difrent taks... or something like that.
Tyranids, Necrons, Orks are not avalible to choose from becouse they are either to Alien, to silence or to agressive. Whould you like to play a millenia old chunk of metal?? much boring.
But like if you choose some Imperial the "HOLY DICE" will see which way you are going to take, as a space marine, a daemonhunter (which is on of the hardest to become in the this RPG) or an normal Imperial Guard.