You can now get WW2 strategy game Hearts of Iron 4, Early Access pirate shooter Blackwake and sandbox RPG Portal Knight as the early unlocks for July's Humble Monthly Bundle. Subscribers can play the games now, or if you want in for one-time only, it'll cost $12.
Hearts of Iron 4 is the standout. It's one of the best WW2 games around: it has all the depth you'd expect from a Paradox grand strategy game while still remaining easy to pick up, as Rob said in his review.
Blackwake is a another good one. Ian played it last year and said that being a part of its multi-crew multiplayer battles has the potential to be "one of the most exciting multiplayer experiences in gaming right now". He liked how the design necessitated teamwork—each member of your pirate crew can only do one job at a time, which means you have to communicate and co-ordinate in order to keep your ship afloat. It sounds like a lot of fun.
Portal Knight is the one I know the least about. It's a block-based co-op RPG about building, crafting and slaying enemies.
Grab the early unlocks here for $12. If you subscribe to the monthly bundles, you also get access to the Humble Monthly Trove, which includes all Humble Originals and a selection of other DRM-free games. The full list is here.