Developer, Rigid-Soft Studios, are releasing an Early Access version of their Zombie Survival game, Lifeless. The MMO while lets you take on the undead is available right now for $25.
We originally intended Lifeless to be free-to-play but after exploring it a little more, we decided it would be best to just make it a one time purchase. This is for several reasons but the main ones being the cost of server maintenance, support and development. The other reason is because we quickly realized we would have to turn Lifeless into a pay-to-win game if we even wanted to survive the first month with all the costs and that is something we are strictly against!
There is no expected date for a full release of the game, however feedback from early players has been rather positive so far.