For one thing, they're never black, the rule of perception asks them to be dark blue or eerie purple, or strangely backlit. They end up looking like a "space hurricane", a swirly energy thingy, or a literal giant rip in the fabric of space. Some sci fi writers have a hard time differentiating between a black hole and a worm hole, and forget all that stuff about time dilation and event horizons. Others overcompensate because they think Gravity Sucks, and assume that you can't orbit a black hole because devours anything within a million miles.
See also: Do Not Touch The Funnel Cloud
How it really works:
They look like nothing, black inky nothing. Should you be unlucky enough to enter a real black hole, you're pretty much just dead. You'd disappear into the event horizon of a dark spot in space. Nothing to see here folks, move along (if you can). Before you die, you'd get all stretched and squished, and time would slow to a crawl, but you might not notice. For more information, see Black Hole.
Maybe, given the right tech, and an extremely resilient ship made of unobtanium, and a careful approach vector, you may be able to survive a trip into a rotating black hole and travel to a mirror universe, but only if you specifically did a lot of research and preparation to do so, because the smallest mistake would spell your doom. It's a one-way trip, which means there's no practical way to test the results before you go in. You gotta have faith, or stupidity, to try it.
Game and Story Use
- As with all the subtropes of Space Does Not Work That Way, you have a decision to make, largely based on where you stand on mohs scale of science fiction hardness. Space Opera and other versions of sci fi lite can get away with a lot of craziness around black holes, and intentionally silly or funny games can take that even further. Are your inspirations Star Trek and Star Wars -or- Gattaca and 2001? (Or, for a wackier game, Hitch-hiker's Guide and Futurama)