There has been a small subset of online accumulation games released over the last few years. These games are typically solo projects with the goal of clicking on a button to get more points to upgrade things to get even more points. Prominent games like Cookie Clicker hurtled this genre into wide popularity. The genre moved a bit with the advent of Candy Box and Candy Box 2 - two excellent games from solo developer ainwey (seriously, both games are freaking ridiculous if you invest a little bit of time into them) that put players into actual worlds with characters and quests.
Enter: Kittens Game.
Kittens Game by internet user bloodrazor essentially combines the accumulation genre with Civilization, tasking players with guiding the development of a fledgling band of kittens into a thriving society. Players start by gathering catnip by clicking a button until they can begin planting catnip fields, automating the process. Soon huts can be built to house more kittens, government can be established, and technology researched. Eventually the kitten civilization putters along, generating culture, establishing a religion, and interacting with the other races that inhabit their world.
Interestingly, there appears to be some sort of story to Kittens Game if the player takes the time to piece together clues left in the building and technology descriptions (most of the content seems to be cat-puns, though, you have been warned!). I can't say for sure if there is an ending or even if there IS an ending as I have had Kittens Game running for several days on my browser (you can save and come back to it at your leisure) and have yet to discover anywhere near all the secrets this cat-based game holds in its paws.
It's ridiculous, soothing, and satisfies that primal need many feel to press buttons to make progressively bigger numbers. Give it a shot if you have some spare time or a spare tab running in the background of your computer.