I checked out Miner 2049er, because I never had an Atari.
I see ladders, the ability to kill the creatures, no keys and no exit.

And the whole fun of manic miner was whatever was going to try and kill you next,
penguins, ball-balancing seals, toilet seats, kangaroos, steaming balls, fluff balls, bunnies, rotary phones, a flying eye, a credit card,
and then you end up in the intro screen as the last level.