I've used Peercoin which is a fork of Bitcoin but with pos for securing the chain and pow for distribution. I find it pretty neat. It has a small chain of just about a GiB in size and require very little in terms of compute resources. Unlike Bitcoin Peercoin have no hard cap on its supply instead burning transaction fees and rewarding stalking with minting new coins. This solves the problem of what will happen when bitcoin won't issue an reward anymore while preventing overuse of transactions due to deflation. Controll of the network lies with it's holders unlike in Bitcoin where owners of large mining farms decide what proposals should be accepted.

It was a fair non cash grab kind of a coin announced ahead of time giving everyone an equal chance to be first on the chain. No initial coin offerings or other marketing hype to pump the price to the moon. It lives a quiet life nowdays since there isn't much to say about it. It can do everything bitcoin can do and has less flaws. Unfortunately for Peercoin Bitcoin flaws are non-critical and do not matter to most users. Being first gives Bitcoin powerful legitimacy and network effects which clones can't match. Fortunately for me I hold both so it's not a big deal but it's a shame when good projects fail to bring adoption.

Peercoin still got active development though so it's not dead yet. I find it enjoyable to hold and be able to play with.

Hi!
I'm wondering what would happen if a hacker had control over more than 50 % of the networks hashrate. What could he/she do to the network? Can he move people's funds without their permisson? How long do a hacker need to control the network to make his changes irreversible?

Thanks in advance!