Modding is one of the better ways to get into coding. I myself have fond memories restoring cut content to Fallout: New Vegas.

It's unfortunate that modding support is relatively rare among game developers. Blizzard used to do quite well in this regard, in their W3 era. And tools they packaged with SC2 weren't bad either. But nothing since then.

Obviously there is Valve, that goes without saying.

Recently, CD Project did make some moves in that direction, but nothing close to what Valve is offering.