When you need to abstract elements such as wealth, durability, supplies, and so on, you can use this procedure.
For the purpose of these rules, I'll call all of the above Resources.
Your Resource pool is a number of d6.
Whenever that Resource is at stake, spend any number of d6 from your pool. Roll all of them and keep the highest.
- 1-4: you get the result desired from spending your resource. You can Push your roll by rolling +1d6 (not from your pool);
- 5-6: same as above, but instead of spending all dice, spend only 1;
- 7+: there is a problem.
An alternate, I'd say more costly alternate is this:
5-6: same as 1-4 but you spend 1 less die.
Design Advice: scarcity rules are empty when they exist just for the sake of making the game harder for players. Personally, I think scarcity is one of the most material abstractions of time. You spend or lose something as time goes by, as you persist, and struggle. What could make any sort of scarcity rule more interesting is how to replenish or preserve your Resource if that is possible at all.