The document discusses lessons learned from designing Phantom Doctrine. Key points include:
1) Assumptions about scope, budget and timelines led to an unfocused game; the scope should have been re-evaluated frequently.
2) Features needed to be designed around expected usage to avoid repetition and provide clear climactic moments; relying on optional skipping led to underdeveloped systems.
3) Difficulty levels were not differentiated well, with complex systems on easy and a simpler experience on hard.