At first glance, Ylands looks like your standard survival game: you wake up on a desert island ready to craft tools, gather resources and fend off aggressive wildlife. But what sets it apart is the variety of things you can find and craft (diving off the starter island might net you some scuba gear and a treasure map, for example), as well as a game editor that lets you create an endless number of scenarios.
Basically, you can set up any island (or Yland, as in 'Your land') however you want. If you get bored of taming horses and brewing potions then you can make an icy race track and send vintage cars skidding into the bends. The terrain is fully modifiable so you can siege a castle, battle pirate ships, build a platforming puzzle or fling horses for miles using catapults. The game editor is built right in and you can play through other players' creations in the Ylands Workshop, which is surely where you'll get the most fun. You can switch between single-player and multiplayer on the fly, which is neat.
The Early Access version has just come out on Steam, and it will set you back £10.40/$12.00. For that you also get $20 worth of credit at the in-game store to buy cosmetic items for your character. The final version, which will be more expensive, will come with a new world to explore as well as NPCs.
Looking at the early Steam reviews, most people are impressed with the game's flexibility, but the main gripe seems to be with the performance and optimisation, particularly in the laggy multiplayer. Still, it's early days yet. Developer Bohemia Interactive (from the Arma games) says it will be in Early Access for up to 8 months, which is plenty of time to iron out the creases. It's an interesting concept, and it might be worth a look if you don't mind some performance hiccups.