I'm new to RPGs and I'm part of a group with more experienced players. My challenge right now is to create a short adventure as a one-shot (and that's why I'm asking here and not them). We use AD&D2, but I'm interested in testing GURPS on this story.
My question is about endings. The players will try to achieve a goal, or refuse to do it. If they try to achieve the goal, completing all steps and pushing the final button, I'm planning to make an open final roll to determine the ultimate success or failure of the mission, with the odds of success based on the time spent, number of safety measures achieved, right tools, etc., but no way to ensure a 100% chance of success on this final roll.
To make it simple, just imagine they will try to defuse a bomb at the end, so the outcome may be "everybody died" or "we saved everyone", with the odds of success depending on what they did leading up to that point.
Can that kind of ending work for a one-shot, or does it just create frustration if they did well and just got unlucky at the end?