The feeling of satisfaction you get when you play this game well. 
As you may of guessed playing this game today as well as I have has made me happy. 
  
I was on a roll and defeated 3 of the archdemons and only died during the first battle; albeit I died numerous times, but I defeated the bastard.

The huge scale of most of the boss battles makes for some great bonerific victories as well.

Yes, especially that damn spider, and the scary fire man, grrr. I can never get the pattern down and end up eating huge amounts of grass. Tower Knight is easy as heck but some bosses never get easy. Or sections for that matter. Damn you, cliffsides with skeletons and flying mantas, yuck.

Most of them are really fun, but I found the dragon god fight to be a bit anticlimactic. As long as you timed it right you just ran through it.

Also some dude invaded me, which scared me as I didn't think I'd be able to overcome another human player, I even tried to hide, but he found me and we dueled right next to a huge arrow machine and I won :D 
Then to make the experience even better, the dude mailed me to say 'well done' on my defeating him. What a great guy. 

" Yes, especially that damn spider, and the scary fire man, grrr. I can never get the pattern down and end up eating huge amounts of grass. Tower Knight is easy as heck but some bosses never get easy. Or sections for that matter. Damn you, cliffsides with skeletons and flying mantas, yuck. "

" Also some dude invaded me, which scared me as I didn't think I'd be able to overcome another human player, I even tried to hide, but he found me and we dueled right next to a huge arrow machine and I won :D Then to make the experience even better, the dude mailed me to say 'well done' on my defeating him. What a great guy.  "

I need to give this game another go. 

Don't you love... To not fight False King? 
 
Dude yes. 
 
Magic spec with Magic Weapons on NG+ Beat everyone besides him... he takes 100 dmg at most. Grinding some STR and got a crushing weapon just to fight him. 
 
What an asshole.

" @AlexW00d said:

" Also some dude invaded me, which scared me as I didn't think I'd be able to overcome another human player, I even tried to hide, but he found me and we dueled right next to a huge arrow machine and I won :D Then to make the experience even better, the dude mailed me to say 'well done' on my defeating him. What a great guy.  "

Someone doing something nice? OVER THE INTERNET? What has this world come to. "

" Don't you love... To not fight False King?  Dude yes.  Magic spec with Magic Weapons on NG+ Beat everyone besides him... he takes 100 dmg at most. Grinding some STR and got a crushing weapon just to fight him.  What an asshole. "

" @Chavtheworld said: 

Someone doing something nice? OVER THE INTERNET? What has this world come to. "

Demon's Souls actually has a pretty great community, probably because the fact that it doesn't hold your hand scares off all the halobros and culladitty heads. "

I know the feeling:) I remember on my first play-through when I got summoned to play as the boss (old monk – Tower of Latria) against another human. At first I thought the game had bugged out, but then I realized what was going on, that someone was fighting his way through the final level of this world to face ME, as the final boss, and that this could very well be my one and only chance to get some secret item for winning. The fight lasted for 25 minutes. He gave everything he had to beat this world, and I for the chance of being rewarded with something rare. I have never experienced an actual adrenaline rush like that from playing a videogame before, and probably never will again. I won and immediately after got invaded by another player. Defeated him as well and ran back to the nexus as quick as possible. Put the controller down and had 3 smokes in a row with trembling hands while calling a friend to share the story. Amazing game!