There is the type of sentences with the word UNLESS.

Example:

The kids will play outside unless it gets too cold.

Main part: The kids will play outside (future).

Conditional part: unless it gets too cold (present simple).

The word unless contains a negative part in it. Something that goes after this ford – ruins the main part.

For example, I will pass this exam successfully. This is the plan.

UNLESS (what might ruin this plan?) I forget everything.

First Conditional