There are a couple of ways to deal with licensing your engine as far as not giving away the WHOLE thing all at once. Some folks (Power Render, for instance) will license the "object code and tools" at one price (affordable) and license the source code at another (EXPENSIVE!).
Personally, once I finish my engine and tools I have no intention of providing the source code! Sure, it may lose a licensee or two, but it''s less of a support nightmare to just have one or two versions out in the field rather than each place having some hack of your original you now have to try to deal with.
If you provide DLLs or libs, docs, and tools you should be in good shape and not end up revealing everything you''ve done for the past years... and you don''t have to worry about someone making a mess of your engine and advertising it as "made with the foo-power engine" (and the bad publicity such a thing can bring).
Not like someone died and make me Carmack, mind you
Hope this helps some!
Anyhow I was just hoping for a bit of input from you folks...hoping. I'm a programmer for a new game company debuting around 4th quarter 2001. Anyhow the company I'm working for is currently developing anew library of games, and for these games we are developing a new engine....sorta like the unreal, or quake engine.....but an all original system and features...no reused source but from scratch!
Let's skip the babble....we have two lead programmers (what?)....and the company is giving us the right to choose to sell the potential engine (SDK) or keep it only for our games. Ofcourse we will make around 2-3 games before we would even think of releasing the for sale - license. My question is....is this a wise investment (selling the engine)? Or should we be bad and keep the glory? I don't have the whole say-so but I am 50% of it!
All input is appreciated. 
