I suppose having less endings if you want to keep it small, cut some down or use ideas for non ending paths or scenes. You can keep a story small and focused primarily on one event or goal too even if it has a lot of moving parts. Sometimes a project just expands and now you have a larger storygame though. Always best to start off small though if you can.
When I outline I just make a basic outline with branches and notes on variables and what pages and branches link to what. Length really has nothing to do with engagement, unless it's just meandering and off the walls. But if the story is engaging through character and plot and decent enough writing it should be fine. For a newer writer it's better to get the knack of that with smaller stories though before doing something bigger though usually. Unless you're just a fucking wizard then have at it.