The “Gap” as it is known in Hollywood was pioneered by Robert McKee in his book Story. We highly recommend that anyone interested in learning how to write excellent scripts buy and read this book. We will give you the basic principles here.
The Gap is a moment when a character attempts to accomplish a task, be it simple or difficult and they are prevented by an obstacle thus creating a Gap between them and their goal. Gaps should continue from start to finish in your script and should be the mechanism used to guide your characters into difficult decisions that let the audience know they have talents for solving problems.
Gaps should also get bigger as time goes on. Once you’ve gapped your script from start to finish, a chart of your gaps should be possible. You will want to make the gaps seamless in your script, meaning believable to extent depending on your genre. If you are writing a fantasy script where anything goes, you can create gaps that are outrageous whereas if you’re writing a script that rooted in reality on all fronts, your gaps need to be 100% based on reality.
A good way to design your gaps is to align them with your characters overall goals that should also be more grand as time passes. For instance, a character might run out of coffee in the first scene, thus forcing them to go to the market where something happens. Towards the end of your script they might be trying to deactivate a nuclear bomb and the gap can thus be more complex involving the need to learn something about the circuits that control its detonation mechanism.
If you want to borrow a mechanism in video game gapping, you can make a series of gaps increasing more difficult until you reach one large gap, then easy the difficulty down half to build it up again in difficulty for your next big moment. This method of stair-stepping your gaps allows the audience to have a release from the overall tension to relax and thus build up more neural chemicals to enjoy your next big moment.