So right now, market forces are mainly interested in making Space Engine the successor to Celestia, rather than a game? I don't mind it that much personally -- Celestia needs a successor with better graphics.
I can't say with certainty what the "market" wants (there are so many niches within the software market that you can probably find success no matter what type of product you want to make, if you make it well and market it well), but SE was always a sort of "spiritual successor" to Celestia, and its planetarium functionality always had priority over any game development. This has been the plan for many years. Planetarium features added as the engine develops, and when the engine and planetarium program are sufficiently "complete", then development of games can begin.
I don't know to what extent financial realities will affect that sequence of development, but that's what the plan has always been.