This can end up like DLC in my opinion.
Its a great idea, but it can be really abused by companies if they so wish to do.
Doing Alpha's right is a smart thing, minecraft was pretty much the start of all this, but i feel this is more fitted for the more indie or smaller companies to take advantage of, you can sell your game cheaper while still generating money in development to make the game better and bigger than it would have ever been on its own, fans will help with troubleshooting and find bugs and even help make the game themselves with suggestions and bug reports and not only that but they'll spread the word around and eventually the game could become massive, alot bigger than it could have on dev budgets and advertisement, i got Arma III in Alpha on steam, when it came out and it was only £20, i know this games going to be an absolute masterpiece, i've helped them support themselfs and i'm helping to dig out bugs while having a great time gaming, so it does work for bigger games as well, i cannot wait to see this in beta form and then to finally play it released with a brilliant story mode on top, the game doesn't even have a release date yet or nothing but i can happily enjoy whats been done so far, its actually pretty fun to do.
However i'd imagine some companies could take advantage of this, imagine instead of getting your free access to the multiplayer BF3 beta like we did, we'd have had to pay for it and then imagine having to go and buy the game again once its released to get the story and the other maps, i can really imagine that sort of thing happening, "pay to play early" with the advantage of having your multiplayer XP put into the final game you buy once its released i'm pretty sure this could start happening with the bigger companies by next gen and many people would go for that option, its just like DLC, its a brilliant idea and it brings pc like expansions into downloadable content for you to buy, things like episodes of liberty city, borderlands 2's cheap season pass and fallout and skyrim dlc, (besides hearthfire) however you can end up with really sour dlc like capcoms famous on disk DLC or the 800ms horse amor in oblivion, we'll need to take the good with the bad.
Good COD .gif