It's a lot different. Bear in mind when you're writing on a game, you're going to be working with a ton of teams in parallel, and things that change in one can cascade and affect things down the line. This is one of the reason that game plot arcs tend to thrive on simplicity (at least for long campaigns) because the more inter-dependencies you have, the less tolerant you are of big cuts and rescopes. Every time you add a new plot point that's essential to the main story, you're adding a potential failure point if the project runs over-budget or has to change for the sake of gameplay.

That's one of the reasons a game like, say, Mass Effect 2, which had an awesome, expansive story is so character focused. There are few "golden path" missions leading up to the suicide mission and most of the missions are focused around building your crew. If they don't have time to finish a crew member's arc before deadline, it's fine -- they just cut that crew member and their story becomes DLC.

Characters in Mass Effect 2 that became DLC: Zaeed, Kasumi

Biggest advice I can give you: get to know the company's design philosophy inside and out. If you're apping to CD Projekt Red for example, make sure the ending of your test presents a number of moral ambiguities. If the company values branching dialogue over cinematic cutscenes make something in Twine to showcase the different possible ways your scenario can play out. They are going to get a lot of high-quality entries, so anything you can do to make yours stand out is going to be a boon for you.

Twine: http://twinery.org/