Operation Killstorm is the first mission in Deathwatch: Overkill. Here you can see the leaks in English and take a look at the board and how the game plays. Thus far with a good selection of models, it seems this Deathwatch Overkill very much could be a intro step into 40k. The rules should be very familiar to 40k fans, with movement phases, assault phases etc.
Thank you A. Crynyd for linking us up on this!
Check out Deathwatch overkill leaks of Gameplay here