Back when Tomb Raider Chronicles released in the year 2000, the PC version included the level editor used to make the previous title (The Last Revelation). It had a pretty lengthy learning curve but I was very dedicated to teaching myself how to use it (I still remember we didn't have a printer so I summarised the included e-manual - lots of writing!). I was pretty into it for a long time, but sadly never published anything online. The community is actually still going strong however, and modders have taken the editor to pretty amazing places (it does have it's limits though due to them not having access to the source code). The gameplay below of an upcoming level is a good picture of the level/game qualities achievable with the state of the editor today:
