diceless

The last basic mechanic for lack of a better term is diceless. No random factors, though this doesn't mean there isn't any hidden factors. On some level all games have this. Through using abstractions they determine how the charter or world works.

The most well used is the HP and the other names that is in the end health. It works on the principal that as long as you have X you are fine. When you get damaged you lose some of this resource (or in some case gain until you reach a limit) you have to trade it in until a number is reached the something happens. This is the diceless mechanic, it is as simple as that, you trade your resource for or because of an effect. Another example in DnD is the spell system where you are limited on how you can cast spells based on the max level you can learn and how many on any individual level. In some cases you can sacrifice any spell level for a certain type of spell as long as it is the same level or higher.

The key factor is there is no random chance. This does not prevent it from working with random chance, the HP example is reduced by a few dice roll. The roll may even be effected by a stat which is not random during game play and may help or hinder how a roll can go.

Almost all games, unless they are dedicated to diceless, use a combination of the three mechanics if not all.