Braid (Jonathan Blow's previous title) was in development for something like 4 years and technically it was significantly less ambitious than The Witness appear

Braid (Jonathan Blow's previous title) was in development for something like 4 years and technically it was significantly less ambitious than The Witness appears to be. In the end it turned out very nicely polished and was one of the best games I've ever played. Not all years-long development cycles are signs of trouble; generally that only applies when you have task-masters death marching a burned-out team along to various failed deadlines. When you have a single or small team of creators iterating on a core game idea with the means to actually release the title "when its done", good end results often occur.