@pathunstrom
Everyone's already mentioned Terraria, but yes, that might fit, though blood moons/goblins/pirates/eclipses could maybe count as "hard calendar" systems? they're entirely RNG, but they're not really avoidable or skippable either, and they tend to prevent you from doing anything else until they're done. also stay away from the The Constant and Zenith special seeds, since those add a hunger mechanic.
I really like Fallout 4 as well. It's got a blend of town building, exploration/scavenging, and FPS combat that I thoroughly enjoy, and, aside from the repeatable radiant quests (which many people limit or just disable with mods), I don't think there's any of those time systems (though you'll want to avoid survival difficulty, since that adds not only a hunger mechanic, but also a thirst and sleepiness mechanic. similarly to the thing in Terraria, this was added after release, so it's not like the game is missing something without it.)
Finally, the next closest thing I can think of is Noita, which is kinda like a blend of Terraria, NetHack, and a falling-sand game. There's not really any construction you can do (not easily, anyway), and you're not really expected to return anywhere, but you ARE expected to gather materials and build them into better weapons: the wandbuilding system in this game is absolutely deranged in the best possible way. Noita is a game that expects you to exploit its mechanics in the fullest sense of the word. The main issue is that it's absolutely unforgiving, with very limited healing, mandatory permadeath, and a whole bunch of complicated and intersecting mechanics it doesn't explain at all that can and will find new and exciting ways to kill you like a rat in a power box. The only hunger mechanic that exists is added by one particular perk you can select in between levels, which is near-universally considered a bottom-tier pick to always just skip unless you're going for the 100% achievement
