Out of interest, don''t 2 of your clauses seem to potentially contradict each other? Namely:
"protect the work contributed by members, so the ''team'' can''t take advantage of somebody." (which implies that each member owns their own work)
and
"protect the team from having to stop/replace members/work because a member leaves and wants to take their work(engine/models/music)" (which implies that the team owns the work that is submitted.)

You''ll want to clarify this. You might want to specify that a member grants the team a ''permanent non-exclusive license'' to use the resources, or something like that: basically, that both the team and the individual member can use the submitted resources, whether the member leaves or not.

Go with "open source" and put distribution $$$ cap on your binary while the source code remains free of charge and avail. to everyone.