Recs.
Updated
Cookie Clicker is a Javascript based incremental (passive/idle) based game where users click on a cookie in order to earn cookies that can be used to purchase tools that earn more cookies.
Specs
Pros
Pro You never know what is next
Each upgrade costs more and more cookies to purchase and each hidden upgrade is not made available until you reach the amount of cookies it costs, so no matter if you need 100 cookies to purchase a new Grandma or a trillion to purchase some other tool you will always be left feeling like you just need to reach that next milestone.
Cons
Con Some may see the game as not a game
Incremental or as some know them "idle" games are not always received well by those looking for something with a bit more skill needed, basically the game will play itself at some point and from that point forward which can be pretty boring. So for those that are not interacting with the game that often (no clicking, no checking in often) it can be less of an interactive title than what some are looking for.