The Kerbal Space Program is an open-ended spaceflight design game. The ever-cheerful Kerbals don't seem to mind my inept attempts to launch them into steady orbits, possibly because I tolerate their capacity to develop rockets, yet not have ladders.
Part of the joy of the game is the hilariously-labelled parts. For example:
The Pegasus I Mobility Enhancer, known in some circles as a "ladder", is a state-of-the-art vertical mobility device, allowing your intrepid crew to scamper around the exterior of your ship like highly caffinated rodents.
Don't let the name fool you: a mobility enhancer is essential for getting in and out of spaceships without doing fatalistic leaps in an effort to hop back up to the door.
Notice that this Kerbal explorer (or Kerbalnaut) has successfully landed on an alien moon. Then note the smooth sides of his craft. How would you solve this particular dilemma? For this particular Kerbal, this situation calls for a lot of well-timed, carefully-aimed leaps.
Unless those leaps get a bit too enthusiastic, and the Kerbalnaut achieves escape velocity off the rocky moon. ...whoops. That's what he gets for being too cocky to use his rocket pack. Ah well, make a note: when designing for the asteroid lander mission, ladders are not optional.
Screenshots from Kerbal Space Program provided by Joseph Henderson McCance.