Is there any board out there that gives the option of assigning missions instead of conquering territories? For instance, my mission is to eliminate the red, someone else mission is to conquer Europe and Oceana, etc. I played that mission based risk back in the 90s.

There is a newer feature called Win Conditions, that could be used to create certain types of what you call missions.  It hasn't really been used that much by most designers at this point, but then there haven't been that many boards created in the last few years (maybe two or three dozen at best.

I once suggested that if the Cards could be included in the factory mix (factories are a designer tool that enables many advanced and unusual non-risklike features) , many more mission related objectives could be added.