Is dreamseeker.exe open in the task manager's process list? If so, can it be closed? If it's there and can't be closed, the culprit is likely Avast, which has been blocking Dream Seeker on some people's systems for a while. You'll have to add the BYOND folder to Avast's exceptions list, and once everything's fixed, report the false positive to them so they can fix it.

If dreamseeker.exe is opening but crashing, there should be information in the Windows event viewer documenting the crashes. What I would need to know then is what module is crashing, and at which offset.

If neither of those is the case, we'll have to collect more information. Walk us through the steps you take to launch a game, and what happens at each step. Make sure you have Task Manager open while you do this, so you can check if dreamseeker.exe ever opens or not.