How to Balance Gameplay and Story in a Trailer
How do you balance story and gameplay in a game trailer? It depends on a number of factors:
Game genre
The "hookiness" of the story & gameplay
Whether the game is original or a sequel
This will sound incredibly obvious, but looking at the game is the best way to know what a trailer should look and feel like. After all, the trailer should be reflective of the game experience. Think of the balance of a story and gameplay in a trailer as existing somewhere on a line where on one far side you have a trailer which is 90-100% focused on story, and on the other is a trailer 90-100% focused on gameplay:
On the far story end of the line I put visual novels (even more extreme would be Twine games). These games consist of a lot of text. To play them, you mostly just click dialogue choices and hypertext. Once a trailer indicates a game is a visual novel, it doesn't need to spend time explaining how to play the game. It has to focus on the unique story premise, characters, and maybe give some indication of branching storylines (if they exist). For the trailer I made for Neo Cab I mostly focused on the story, but included a brief section showing that you pick up different passengers who then give you star ratings. On the story/gameplay axis I'd put this trailer slightly closer to the gameplay side, but still about 90% on the story side.
On the far gameplay side I'd put puzzle games which are pure game mechanics with often little to no story. For example, a game like Tetris. It doesn't have a lot of game mechanics to explain, but it also has no story to focus on at all, so the trailer would be pure gameplay. Or in the example of Tetris Effect, pure vibes (more on this later).
A puzzle game like Manifold Garden is also far on the gameplay side since it's mostly about solving puzzles by switching the direction of gravity, navigating non-euclidean spaces, putting cube "keys" into receptacles, activating lasers, etc. I'd put this SLIGHTLY closer to the story side, but it's still just a game which is focused on gameplay. A game like The Witness is also in a similar space as Manifold Garden. There's some story implications and philosophy, but mostly it's purely about solving puzzles.
Where a trailer's story/gameplay balance should sit gets more ambiguous for games which sit somewhere in the middle. For example, the Professor Layton games have a lot of story, but they also have a wide variety of brain teasing puzzles. Between story/gameplay I'd put Professor Layton games around a 70/30 or 80/20 split. The reason is because the story is the hookier part of the game, and the puzzles have a somewhat tenuous connection to the events of the story. A game with the exact same brain teaser puzzles in it with a different story would not be a Professor Layton game. But you could make a Professor Layton game with different puzzles and it would still be a Professor Layton game. These games are almost like visual novels because the way you play the game isn't THAT important. You'd just need a handful of shots of the brain teaser games, but you don't need to explain how any individual one is played.
Say you have an Isometric JRPG style game, I’d put that mostly on the story side because the hook is usually the premise, setting, and characters, not the mechanics. Also, fans of the genre already have a idea about the gameplay tropes. They just need to know those typical gameplay bits are there, but don’t need you to dwell on them). An exception is if your RPG has some unique mechanics to it like Undertale's battle system and its dynamic changes to the story based on how you play. I'd put Undertale closer to the middle of the line because story is very important, but how it plays is a differentiator that should be understood.
A metroidvania is going to skew towards the gameplay side. The game feel, the power ups and abilities. Yes, of course we want to know how Silksong will flesh out the story of Hollow Knight, but because we're going to play Hornet, veteran players will be curious what it feels like to control her. Rogue-likes will also tend to skew towards gameplay. Spelunky 2 has a very basic story setup, but it's still mostly about the gameplay. I'd put the story/gameplay split of Spelunky 2 at 80/20 at MOST. For the launch trailer I used voiceover and journal pages to show more of the story, but it was still mostly about the gameplay.
I think all AAA games skew somewhere in the middle, but more on the side of story. Oftentimes we already know how the game will play (especially if it’s a sequel) For example, for Marvel's Spider-Man 2 I’m very curious how the story unfolds because that will determine the things I DO in the game, who I fight, what the missions are. I’m not expecting the gameplay to be wildly different so I don’t need THAT much time on the gameplay, I just need to see what’s new.
The more unique the gameplay is, the more you have to spend time showing it or explaining it. So when God of War changed the camera perspective to be over-the-shoulder, it was very important to give the gameplay a lot of time even though they could easily fill a trailer with the cinematic cutscenes. God of War is a very story driven game and it has a lot of "game-y" mechanics, but its trailers tended to skew towards story even if the two are fairly balanced. Another reason AAA games will skew towards story is because the moment to moment gameplay can be full of repetitive dialogue and barks that break the polished cinematic presentation.
Another balance you can aim to strike with a trailer is the split between raw information about the game, and the game's vibes. This is usually based on how difficult it is to understand the gameplay. The more difficult to understand, the more information you need to present. The less difficult to understand, the more freedom you have to make a stylish cinematic trailer. 101 or Overviews trailers tend to be very clinical in their presentation of game mechanics. Think of the GTA trailers that walk through every new feature of the games. Those are pretty dry trailers even if they provide a lot of information. Those trailers are heavily skewered towards information. Though, those go against what I initially said about game complexity, because GTA games are very easy to understand (as opposed to a Paradox Strategy game)
Teaser trailers or moodier trailers like the famous Gear of War "Mad World" trailer or Dead Island skew heavily on vibes and story. They don't tell you specifics about the gameplay, but they're chock full of mood. Those make sense because they're games based off action and violence. A game trailer for Journey is also likely to be heavy on vibes, but that's because of the mood they're trying to set which is reflective of the game. Oftentimes, the more famous a game becomes, the more its trailers can live off of vibes and abstract imagery. Think of how commercials for products like Doritos or NIKE often don't even show their products anymore. They've transcended the basics of advertising: "This is what the product is."
The easier to understand the gameplay, the more space you have to make a trailer which relies heavily on feeling. I think the trailers for the game Somerville are kind of like this. It's a 2.5D game with a lot of familiar images and once you see the character move you have a general understanding of the gameplay. This trailer for Terra Nil has a nice balance of information and vibes which works for its chill tone, but necessity of explaining this novel mechanic.
As always, the balance for your game depends on a number of things (as listed up top). But the answer always lies somewhere in your game. Try to first find the divide between story and gameplay in your game. Then once you find that divide, consider how much your gameplay needs to be explained, and find the balance of how much work your trailer needs to put into either showing how the game works or explicitly explaining it via text or voiceover. A more experienced trailer director will be able to make a trailer which relies less on title cards and voiceover, but this should still be a good place to help you find the balance!
