Personally I never buy a game I can't play the demo of first, apart from console titles; even then only GameCube ones are games i buy without trying, my mates have X-Box and PS2's so i wait til they have them and try them that way.
If your serious about selling your games though, there are a few things you need to make sure of in order for it to actually do relatively well.
1. Screenshots & Graphics; your game will be judged waaay before anyone actually plays it based on screenshots. Therefore you *must* make sure that the quality of the game is nice, and that you show off some of the most graphically impressive areas.
This might seem a little cheeky, but you don't want people turning away because your game looks bad.
If I can I will find two identical types of DB/P games created one of which is good and the other bad and explain why.
Right now don't have the time.
2. Additional Media available. A Game demo REALLY helps a user want to buy something as long as it doesn't reveal the entire game and just gives them a taster. Also rolling movies tends to also sway because you can see how the game looks in action not just statically.
3. Professional looking website. As most games are distributed through websites you must make sure yours is appealing and nice to use.
Again when i have time i'll go through a few websites and give some good and bad examples.
Generally speaking though try not to use dark colours, unless your game actually has a dark theme and even then you want to work with very good graphics to create the atmosphere of it being dark. Try not to over complicate it with too much flash or with gaudey graphics. Simple sites are quite frankly far more appealing than OTT ones with bad graphics...
4. Price & Market... Try to keep the price of the product aimed at not only your key market but also try to make the specifications you require also within that key market.
An FPS will relate to the Power Gamers, who have lots of power in thier PCs (but are often tight fisted buggers when it comes to games); so push the graphical envelope whilst offering the game at a cut-price.
A puzzle person doesn't care for state of the art graphics they just enjoy a challenge, pander to this and make sure it cna run on low specs; this market will often pay mid-range prices.
RPG markets are weird, they'll pay buckets for a game provided it gives them a long experience; yet they range from low-end to high-end pc users, so it is best to make the graphics very scaleable whilst kinda gouging them; and if it is an online game then sell the game cheap (or give it away free) then charge them double your costs for running a server for them
Alot of games retail is making it appealable to people without ever even playing it; if you can remember this then you might have a good carrer in Publishing (who earn a hell of alot more than us developer grunts)
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