I really enjoy the game Minecraft, and I think it’s a good example to showcase loops and arcs. The basic loops in Minecraft include movement, placing or interacting with blocks, and destroying blocks. These interaction loops build into skill chains that constitute combat and advanced movement (jumping and running, climbing ladders, MLG water bucket). Overall, there is a larger arc over the entirety of the game (getting to the End and defeating the Ender Dragon), but most of the time it is up to the player what arcs and loops they’d like to employ. I think that’s the beauty of the game – players can choose for themselves when they’ve mastered a skill, or when they’d like to start a new arc of building or exploring. In this way, the game is always tuned optimally to what the player wants or needs, as they are their own game architects.