Aliasing dnd → dungeons_&_dragons
Link to alias

Reason:

Seems to be a somewhat common shorthand for Dungeons & Dragons like "d&d", which was also aliased to it.

Aye, all the other forms were aliased, just not this one.

As abbreviations go, that one is quite common for it, I'm surprised it didn't get got before when the other one was. Approved.