Our approach to F2P is, as we're developing the game we will release updates that anyone can download for free. Updates are either in the form of mini-demos (we show off and allow players to test an individual feature of the game that's in development) or full re-releases of the game itself (where the feature is developed and debugged enough to be put in with the rest of the game). These updates can be graphics improvements, new tech installments like middleware (Example: Euphoria, DMM, HumanIK, fluid simulations, etc.), bug fixes and other changes that improve the game as a whole.
The moneymaking bit is in allowing the player to buy character packages called "Heroes". Each hero has his own model, backstory, and has a number of perks, weapons, items and/or "tilesets" (explained below) that he can use in-game. Some characters might come with 6 different weapons, while another character might have several more perks than most other heroes.
However, rest assured that while this game is free-to-play, it is NOT pay-to-win. Buying heroes is strictly something you can do to customize and personalize the game to fit your play style. It is similar to unlocking characters in other games (Soul Calibur and Super Smash Bros. come to mind for me) in that no hero is necessarily better or worse than any other; it's just a matter of what you prefer to play with.
In fact, at any time there will be at least three heroes available (we will pick different ones every month or so) that you can play as for free. You can also unlock heroes simply by playing the game long enough; the benefit here is we believe this will cause players intent on unlocking characters without paying to invite their friends, causing viral spreading, and catching the attention of more people willing to pay.
Also, I mentioned that heroes can have their own "tilesets". Tilesets are basically the appearance of your character's building blocks.
As you may have seen in the video, you can build using cubes similar to Minecraft. But instead of being simply a six-sided platonic solid, it can have trim, grooves, trusses, arches, studs, railings, and even physically simulated objects attached. Down the line our goal is to diversify the tilesets to such an extent that it looks like you're building fully-fleshed-out architecture that'd take weeks for a graphics artist to produce.
Thanks for checking out the game.