I'd base the price on the time it takes to beat the game fairly fast (ignoring all side quests). Basically, 20+ hours would be $60. $50 if you only hit 11-15 hours. $40 for 7-10 hours. $30 6 hours or below. Knock off $10, if the game is 2D. Paid DLC shouldn't exist, ever. If base prices go to $70-$80. And if you buy a LE of a game, for a high amount. All paid DLC no matter how late it's made, is free.
Only under special cases would this be voided. Like making Poken Fighter have all 700+ Pokemon. Or if you have 40 characters that can do attack combinations. A game that does fully destructable enviroments. The first entry in a fighting game. That has 100+ characters. And didn't get to build the roster up, over multiple versions. Things like that. I'd also void these rules if the sequel has less content, than the previous game. Like Sims 4. It didn't equal base content/features of Sims 3. The price is dropped by $10.
