These are just some of the objects and hazards that Keen will encounter in Commander Keen: Galaxy Reimagined.
Walking through a door takes Keen to another part of the level. In certain cases, doors may also act as the exit to a level. Some doors may need to be unlocked with a keycard first.
These floating platforms can take Keen to places he can't reach even with the high jumps of his pogo stick. Be careful if you see one that isn't moving - it might not support Keen's weight very well.
Gem barriers can't be passed until the corresponding colored gem is placed in the gem holder. Keen will automatically place the gem when reaching the holder, if he has it.
Switches can do many different things, but most commonly, they either open or close a barrier, or alter the path of a goplat. Most of the time, if the switch's effect is far away from the switch itself, there will be some kind of indicator to hint at what it does.
Keen's grappling hook can catch onto hook points, giving him a rope he can climb up and down just like a pole.
Various kinds of dangerous surfaces exist. Keen will lose a life if he comes into contact with these - and can often end up bouncing off them repeatedly, draining multiple lives quickly. Avoid!
Lacking any swimming gear, water is initially just as dangerous to Keen as spikes or other similar hazards. That all changes once Keen finds himself a wetsuit, though.
These poison dart shooters found in the pyramids of the Shadowlands periodically fire poison darts. The shooters themself are also deadly to the touch.
These barriers are designed to turn intruders, such as Commander Keen, into toast. Those found on Fribbulus Xax may be on a timer, or may be operated by a switch; the more refined ones aboard the Omegamatic can only be brought down by breaking a fuse, and even then, they remain somewhat dangerous.