Quote: "IMHO if you spend the many months it takes to produce a selling game, then why not promote the engine/game making platform that made it possible for you."
Because marketing costs money.
Also note, the license for fpsc sates you have to include referance to fpsc in all advertising, so all your flyers posters, adds for your game must state it was made in fpsc.
also.
Quote: "'This product was made with, and incorporates part of, FPS Creator. All intellectual property rights including copyright in every part of FPS Creator (whether modified or not) are owned and reserved to The Game Creators Limited.'"
Im sure that is stating, make a game, put all your own original art assets into it, but the IP will not belong to you, gamecreators own your intellectual property.
Im going to post this around a few developer web sites because I want to clear this up.