There's a lot of games being mentioned here that had a full run. Let's talk about an actually cancelled game - SkySaga: Infinite Isles. Block game in the vein of Portal Knights that was extremely inspired.

The gameplay loop consisted of using "Keys" on a portal at your home island that would randomly generate a floating island with various objectives on it and a boss, all of which was harvestable for materials and blocks to build with back on your home island. There was a social hub city island everyone could access that alowed access to PvP and a few types of guilds with various combat, gathering, and exploration quests. Crafting was pretty good, allowing you to use metals with various properties to mix and match your own gear - some metals did more damage or applied an elemental effect, some had quicker swing speed, some were durable as armor and others not so much but they increased movespeed or jump height.

The game had about a dozen beta access phases then dropped off the face of the earth, with the server (and how it worked) lost forever. Completely lost to time, cancelled before it could release proper. No other block game has come close to the kind of structural appeal it had for me, and I think about it frequently. There's a few reverse engineering projects in the works but they are stagnant.

I love a lot of the games in this thread but they had an actual release and real servers, you could play them for multiple years. Some others promised a bit more than they delivered, and were cut a bit short by EA or other trash publishers. SkySaga was killed before launch and placed in an opaque prison, truly cancelled.