- Enemy damage output is increased. Creepers will probably one-shot you, even if you're wearing armor. Skeletons and zombies also do more damage.
- Hunger will kill you. Granted, in our regular survival instance, hunger will kill you as well. But...
- There is now a death penalty. If you die in the hardcore instance, you'll be kicked out and will return to the regular world. You'll also be barred from entering the hardcore instance for 30 minutes. I may tweak this timer in the future, but for now it's enough to despawn your stuff when you die if the chunk is still loaded but not so ridiculously long that you completely lose interest in what you were doing.
- You're mostly safe at the spawn. It's underground and protected by WorldGuard. There may also be a story behind it...
- Most hardcore servers allow PvP and encourage griefing. I don't really like griefers or griefing, and I personally believe that griefers have deep-seated emotional issues, low self-esteem, daddy issues, and gain validation from destroying other people's stuff which helps offset the torment they suffered from bullying in the 3rd grade. Then there's the ones who do it because they're trolls and enjoy being accused of having deep-seated emotional issues, low self-esteem, daddy issues, and gaining validation from destroying other people's stuff because they have an exceptionally twisted sense of humor and seek entertainment from others' misery. So, I'd like to keep this as a cooperative hardcore instance. At least, for now.
- I should also add that drowning and death from fire and/or lava are likely to occur much faster. Drowning damage ticks are about a heart higher than in normal mode and seem about a half heart more than in regular "hard" mode. If I can change it, I might even bump up the damage further just to torture you all every time you go spelunking and puncture a lava pool with your pick.
- Inventories between the default world (that's the one you enter) and the hardcore world are completely separate. If something happens to screw up (it shouldn't), don't panic. Nightly backups are made which include your inventory.
Some tips for getting started:
- Your first priority is probably to get wood. This hasn't changed from normal Minecraft. Your second priority is to get food. If you skip the food part, you'll die. It's that simple.
- There are trees near the spawn, but be warned: If you cut them all down and die, you won't have access to any more wood.
- There are also some farm animals in and around the map. What applies to trees applies to them: You can slaughter them for food, but once you're out you're out!
- Your best bet might be to collect grass seeds and try starting off with a small farm. Get enough bread to last you a few days, then begin a trek out into the wilderness.
- Don't travel at night. Stick around at the spawn until daybreak and the spawns stop or die off--then start your journey. If you don't, well, you're probably going to become zombie food or a smoking hole in the ground.
- When the sun starts to go down (that is, BEFORE sunset), start digging shelter. If you wait until sunset, you might have an unpleasant surprise.
If enough trees are destroyed near the spawn, I may end up going full dick and regenerating some of those chunks to keep it fair for new players. Plus, that might discourage people from building close to the spawn so that they can avoid death by sheltering there...
Be warned, if anyone builds too close to the spawn, I will arm Josh with 1000+ creeper eggs, dispensers, and redstone to do with as he pleases.
Also, I may set a 200-300 block radius around the spawn where PvP/griefing MIGHT be allowed to discourage people from building too close to it.
*Rubs his hands together while laughing maniacally* 
