Since it’s a survival-based game, here are some suggestions:
Give an adventure vibe to it.
Make the map large, and make the player to explore around it. I would suggest adding some custom plants, ores, trees, or basically anything.
Add some sort of lore.
People like when there’s some sort of lore or secret hidden among the map. It gets their interest and curiosity piqued. Should make players explore more, and find out secrets.
Add some sort of enemies (or even bossfights).
This would make the game more intriguing and exciting, and the playtime will definitely increase. I mean, you could even make a dragon boss that you have to kill in order to get a powerful sword!
Add a combat system.
Of course, you won’t survive against a monster without combat. This can also merge with the idea of tools, weapons, ores, and other stuff.
Add more athmosphere.
Music can definitely make a player feel a certain and specific emotion. If you add a creepy and subtle ambience, that’s going to make players very cautious, but when you add a calm and soothing ambience, that’s going to make players keep their guard down and relax.
In order to make a good (and interesting) survival-game, you need to keep the player’s curiosity and interest for as long as possible. Building something cool and powerful, like a powerful sword for example, is very satisfying.
That’s all I wanted to say, good luck on your game!