Games are not particularly price-elastic. You can drop the price of a $70 game to $30 and not see a significant increase in sales. That's why they're priced the way they are.
Time-limited bargains like the Humble Bundle and Steam sales work spectacularly well, however.
> You can drop the price of a $70 game to $30 and not see a significant increase in sales
That's because that's still way beyond what most people are willing to pay to play games. You do not reach the threshold at 30 $ where you maximize your audience. It's like saying, "This sports car was 2 million dollars, I am selling it half price and still nobody buys it".
That's precisely why the humble bundle and the steam sales work well. Because they offer you games at a price most people WANT to pay.
A retail game is considered a failure if it sells less than 1m units at $50-70 but the Humble Indie Bundle sold only 450,000 units at an average of just under $6. Clearly there is a market for full-priced games.
Both Steam sales and the Humble Bundle are vehicles for games that have already sold at a higher price and the sales curve is tailing off.
Time-limited bargains like the Humble Bundle and Steam sales work spectacularly well, however.