A game announced years before release is shown in footage that cannot be gameplay, because there is often no playable game yet. What is shown instead follows a recognisable set of conventions.
Announcement footage is made from what exists first
Early in production a team has concept art, character models, an engine and some environments. It does not have systems, balance or a functioning level.
That material is enough to build a rendered sequence in the engine, which is technically real in the sense that nothing was faked, and unreal in the sense that nobody is playing it.
The distinction matters because such a sequence carries no information about how the game feels. It establishes tone, setting and visual direction only.
Vertical slices are polished beyond the game's average
The next stage of footage usually comes from a vertical slice: one short section built to final quality to prove the concept internally and to investors.
A slice receives attention per minute that the finished game cannot sustain across its whole length. Its density of scripted moments and bespoke animation is not representative.
This is a large part of why players report that a game looks worse than its early footage. The comparison is against a section built under different constraints.
Capture conditions differ from a player's machine
Footage is recorded on hardware chosen for the recording, with settings and frame rates that may not match any shipping configuration, and it is compressed for distribution afterwards.
Camera work is also directed. A game is played with a camera the player controls badly and moves constantly; a trailer's camera is planned.
The result reads as smoother and more composed than the same content will ever look in hand, without any single element being untrue.
Scenes are frequently assembled from separate parts
Editors cut between areas, systems and difficulty settings to build a sequence with momentum, and dialogue may be drawn from different moments than the visuals.
Nothing in it is necessarily absent from the game, but the arrangement does not occur. The trailer describes a set of ingredients rather than an experience.
Regulators and platform holders have pushed back with labelling requirements, which is why footage now often carries text identifying its source and stage.
What actually predicts the final game
Uncut play sessions, particularly ones where the person holding the controller struggles, carry far more information than a produced trailer of any length.
Consistency across appearances is also informative. A game shown with the same systems and interface over successive years is further along than one that looks different each time.
The interface itself is a useful tell, since menus and readouts are built late and their presence indicates that underlying systems exist to display.