Its actually quite well paced, due to how you progress through the game in real-time. You start out with access to a limited sub-set of the API, since you cannot build all the buildings/creep parts yet. First you're required to level your room up by upgrading your controller, which to get your first room up to the max level, can take weeks/months of RL time. ( but the game plays itself, and is always running )

The API you use at first is quite small, and takes care of some things like path-finding already, so you don't have to re-build that, though you totally can if you want. Heres[1] an example of some logic to get all your creeps mining from their closest source. Not use-able in a real-world script as the actual logic is awful, but the fun comes from figuring out what does work.

You can check out the API here[2]

[1]https://gist.github.com/ggrochow/db8986d2627d02c992f65cc0cce...

[2]http://support.screeps.com/hc/en-us/articles/203084991-API-R...