This needs a sandbox mode, like as a hidden / unlockable / reward.
Can't wait to see it finihed!!!
I think that's a great idea as a sort of end-game reward!
Perhaps if you were to survive for longer than a certain period, a sandbox mode would be added to the main menu, or add a cheat code mechanic, where entering a code would give more resources (either as a sandbox thing, or as a handicap for if you're struggling)