Originally posted by Las: Games like these are never designed to have an end game and I personally don't want it to have one. The only real end game is strictly up to the player, their personal expectations and preference, and settings.
Some, like myself, can only play it up to about day 30, or long enough to earn ~40 skill points before they start feeling invincible and the game becomes too easy. Others like to build massive fortresses and will play day 100+ and well past max out levels. The real end game for the masses seems to lie anywhere in-between these two ranges.
Yap. Even when the game has a story mode, it's not going to be an 'end' to the game. It's a sandbox; Completing the story will just leave you in the same world free to continue doing as you please.