how do you guys feel about demos? should a game have one at all costs, or can you buy a game purely on youtube videos and screenshots? and word of mouth?

Don't think demos are as useful as people think. I usually go to a netcafe and play the proper game before getting it, it's much more useful.

DEMOS AT ALL COSTS. A video (trailers, specifically) tells absolutely nothing about what's important to a game: Gameplay.

I think indie games and anything innovate really needs a demo to sell it. Another FPS or Western RPG though? Not really. Their variance can easily be ascertained through watching a video.

Most demos nowadays are like 15 minutes of gameplay.

Demos are important for a variety of reasons. The big one is to show people what the game is about and how it plays, a lets play video can let you know if that "innovative new gameplay" is actually something new and not just a Plants vs Zombies clone. But something like Gothic could be misleading as it can't give you a feel for the controls. There is also the compatibility angle; will the game even run on your machine? For a game like Crysis where the advanced graphics possibilities were touted as a major selling point then having a tech demo would go a long way to letting players know what kind of performance to expect and possibly cut down on tech support calls. There is also the lost art of making a demo that sells the game. A good demo should setup the game in such a way that once you get to the end of the demo you want to buy the whole game right then and there to see what happens next. This worked on me for Mount &Blade, I played the game for a few hours and right when things really started to get good I hit the level cap for the demo. When I installed the full game I was even able to pick up right where I left off with my demo character.

I know that a lot of studios claim that they don't have the resources to waste in creating a demo or that the game they are making is just so awesome that a demo can't be made to really show it off. I say that's pure weapons grade baloney-ium. If your game has a tutorial (and it seems that just about every game does nowadays) then it can have a demo. If it's one of those Unskip-able Because It's Part Of The Game Story type of tutorials then that can be even better. Somthing like Fallout 3 could have had a demo that was the whole beginning of the game inside Vault 101, then as soon as you leave the vault you get about a minute or two to see the outside world (controls locked or "invisible walls" to keep you from going to far) followed by some cut scenes of actual gameplay fighting ghouls and wearing power armor and then it says "Go buy the game." How much time would that have taken to make? I bet there are at least a few dozen modders who could knock out something like that by themselves in an afternoon. It would have shown you everything you needed know about the game; how it plays, the controls, is it crash happy, does it have an interesting story?

To be honest, considering that I buy most games nowadays for 10$ or less, I really don't, miss demos that much. Whenever I'm on the fence about a game that costs more, I usually pirate it to see if it is worth the price tag. Sometimes it isn't (Sniper 2) sometimes it is (AC2, which I nearly completed as a pirated version and then bought for full price. Awesome game!).

I believe demos can be helpful some times, but maybe not as much as they use to be. I remember growing up getting demo cd's from gaming mags all the time, and use to play them quite a bit. One of the best one I remember was for Daggerfall. It let you do the Character, Potion, and Magic Creation. It also let you play through a small dungeon, which I remember dying many times in. It let you get the general feel of the gameplay.

I'm all for demos.

I think it's a waste since a lot of people pirate games to try them and wait for sales etc..

The site gaikai is a much better deal, letting people play about 30 minutes of a game in the beginning to get the feel of it. Unfortunately their catalogue is ridiculously small but if it starts to grow it could be a good game demo stream site.

Demos are fine for new games. I can't think it's useful for GOG to host the old ass demos that exist for the games here (due to maintenance), but on XBLA the demo is extremely representative of the game you'll be getting. XBox Indie is the actual game, with a time limit slapped on.

Steam demos I've had good and bad luck with, I do like demos for indies, especially those with oddball seeming gameplay. Krater probably needed a demo, for example. I couldn't figure out what it was before I'd actually bought it. Something like Spec Ops: The Line isn't going to benefit all that much from a demo, I would think (though I think there was an XBox 360 demo for it, at the very least).

So I guess it depends on the game, the more you need to demonstrate vastly different mechanics the more useful it becomes. If you have a platform, such as XBLA, that practically hands you the demo for free, there's no reason to not make one. As for other platforms, hmm, whatever.

Some people will pirate to try with or without demos, it really shouldn't be a factor, others will only want a demo and will not pirate to try, don't rely on community word of mouth from piracy and gaming media if you really need to showcase your game. For every game that gets massive praise 20 or more get a passing mention regardless of quality.

For many contemporary AAA titles, that is substantial.

I always wonder about that one game, its real crappy and the producers know it, so they DONT make a demo, and PRAY nobody reviews it, and then try to pass off some peice of crap game to an unsuspecting shlum like me who buys games without paying any attention to reviews or bad press.