It depends on the game. I can tell you that a certain team I worked on which had about 15 people for a year cost 2.5 million and that's development costs only. That does not include advertising, duplication, distribution, returns etc. I can also tell you that the next title from that same team is going to cost 4 times that, twice as many people working twice as long. It all depends on the game.

For example Warcraft 2 (I think it was 2) cost only like $750k but Diablo cost like 3 mill and Diablo 2 cost like 6 or 9 mill. A game like Tetris could be done for like $20k or less, especially like "Next Tetris" for Playstation which if you take a look at as no art. It's as though it was done completely by one programmer (plus some music)

Basically the more people it requires the more it costs. A game like Warcraft2 had fairly simple graphics so it probably only took 3 artists to make all the art. Diablo 2 on the other hand has not only much more detailed graphics, probably required 10 or more artists but it also has CG video sequences also requiring several artists. It took more than 3 years so lets say each artist made $40k (which may or may not be a low figure) Assume 16 artists, that's 40K * 3years * 16, that's almost 2 million right there and that's NOT including overhead (ie, desk, computer, health ins, 401k, heat, electricity) That stuff can add up to 30% more and that's only the artists. Add 5 to 10 programmers., music people, game designers, producers.

DOOM, remember DOOM, what's it now 6 years old?. That cost probably like 200K and only took 3 people but it was designed to only take 3 people. There are only 10 monsters each with only about 10 frames of animation total if that. The levels are basically laid out in 2D which makes them much much much quicker to build than a Quake level which must be layed out in 3D. And there are only about 15 items. 7 weapons (or was it 5), health, armor, keys, doors and moving platforms. (vs say a character action game like Mario, Gex or Crash where there are hundreds of individually programmed things)

So you pick your game.

One progression might go like this

Cheapest
--------
Puzzle Game (Tetris, Bust-A-Move)
Pinball Game (Kirby Pinball, Pokemon Pinball)
Sports Game (Football, Baseball, ... )
Fighting Game (Tekken, Dead or Alive 2)
Racing Game (CTR, Wipeout (+))
Charater Action Game (Crash Bandicoot, Mario)
Action Adventure (Zelda)
RPG (Final Fantasy 7, (%))
--------
Most Expensive

* A sports game can be cheaper than a Fighting game because you *can* make it with basically one human figure repeated. (just change the jersey numbers and face texture) AND it can have just one simple playfield. Where as a fighting game has several characters and several playfields. Of course you can add tons of stuff to a sports game like commentary, halftime show, stats, etc and then it could alot cost more.

+ Racing games can be more or less expensive depending on how much you put into it. For example at the low end might be Ridge Racer which only has basically 1 track vs Crash Team Racing that has 32 tracks. Other things though can make it expensive (like licensing the cars ie, Gran Turismo)

% RPGs can go both ways. I would suspect that Pokemon was actually fairly inexpensive to create but Final Fantasy 7 with all the effects and CG cost around 40 million.

I'm not sure where games like Resident Evil fit into that mix.  One thing of course is that the better planned your game is the cheaper it's going to be.  If you don't plan you end up doing lots of stuff that gets thrown away and that is time and money wasted.  This is also very true in the movie industry where a common phrase is "every dollar spent in pre-production save 10 dollars in production"

-gregg