I'm working on a game, like everyone else here. I'm trying to settle on a core mechanic.

I have a few options so far, and I might post on some of them later, but I wanted to test the waters for my latest.

Character Traits have a Rank. This Rank starts at 1, and can rise indefinitely. Let's say that a Rank of 10 represents the pinnacle of human achievement. Higher Ranks are reserved for vehicles, Supers, etc.

Task difficulties are measured in dice (d10s). 1 die is easy, more is harder. You *don't want* to be rolling a lot of dice.

When you want to do something, the GM gives you a difficulty- the number of dice you have to roll successfully in order to succeed. You subtract your Rank in a given ability from the difficulty, and then roll the remaining number of dice. If you roll a 10 (or some other value range) on any of the dice, you fail.
 
If you roll no failures, you succeed. You automatically succeed if you don't have to roll dice. I haven't worked out whether criticals are feasible.

I'm worried that this mechanic might seem too negative from a player standpoint. Is that the case? What other effects might this mechanic have on the feel of the game?

What if characters are able to raise the stakes for added benefit? For example, to do more damage, a character could add Difficulty dice to his roll...