Recently been playing Fallen Order. I'm so impressed by it but the key thing that stands out to me is how the level design carefully plays with linearity.

Linearity

Linearity is when you force the player to only go down one path for progression. Often blocking them with various challenges along the way to guarantee they experience exactly what we expect them to experience.

It lets the game designers "know" that you understand a mechanic or rule. Which allows them to make assumptions which in-turn make the levels more interesting.

You need to teach the player how to play. You need to make sure they understand every mechanic of the game. So every level in the first chapter needs to have some example forcing the player to do something in order to beat the level that they will need further in the game.

Linearity also aids communication between game and player. If a level is linear, and you can't continue without solving some problem, its very clear you've reached a puzzle. Its hard to have puzzles in non-linear games without somehow introducing linearity.

These puzzles also let the player experience the joy of figuring out something without aid, while also knowing the problem they are being tasked to solve is solvable and important.

Everybody in the world will see a problem and want to solve it. If you see a level where it is just a wall, and you don't realise you can keep jumping up the wall - you're going to try it right away. And once you try it yourself you've taught yourself and not only do you feel smart (you've figured out something yourself) you also now for sure know how to do that from then on in the game.

Even open world games have linearity in the form of gates. In Minecraft, you are gated by not having specific minerals or materials needed to craft items. These crafted items in turn allow you to reach areas and access materials thatwere previously not possible to obtain. Even though you can physically walk anywhere in Minecraft, you are still on a linear path of progression that was designed (unless if you are playing creative mode).

In GTA you often can't drive over a bridge, because there's a mysterious road closure. You also may find it difficult to access certain vehicles which allow you to access areas.

Games like Braid or the Witness have linear progression in a very zen like way. You always had the ability you just lacked the required knowledge.

The problem is, for adventure games, the methodology of linearity is often quite clumsy. The player notices what the game is doing, and finds the justification for it unconvincing. It can feel like you are just grinding until you get to access the "real" game.

Red Key

Comparing Fallen Order to say Force Unleashed, the level design is completely different. In Force Unleashed you are pretty much on rails from set piece to set piece. Linearity is important to create a sense of progression, but it can also feel like you are being dragged by the heels to the next QTE. It doesn't feel like you are exploring a real place.

Going back further to Jedi Outcast, we had large sprawling levels that loop around on themselves, but in Outcast those mazes feel just as artificial. Once you kill the troopers, the halls are empty, and it is easy to forget what the hell you were doing as all the various hallways bleed together. Often you revisit the same space to unlock a new area via a "key". This tradition carries us back to Dark Forces in the 90s.

Fallen Order is interesting because we don't have any keys. Areas are inaccessible because reaching a certain ledge, or breaking through a particular wall requires a power that the player is yet to learn. The difference is subtle but there's a lot of great qualities to this approach.

For one, it creates anticipation. When you haven't yet found the red key, you don't dream of the day when you'll finally have the red key, and how exciting and thrilling it will be to wield that key. The moment you collect the key, you immediately dispose of it by unlocking a door. Collecting keys isn't that different to fetch quests in World of Warcraft. It is a way of stretching out the games content by ensuring you can't visit and do everything all at once.

In contrast to the red key: a new force power changes how you interact with every other system in that world. It makes the system more complex, more interesting. While it is a gate, it is not fungible with other gates, it is a new mechanical ingredient every time. That respects the player a little more than "you need {color} key to pass this door". Ironically too, preventing you from accessing areas without a specific power actually adds value to that power in the players mind. It creates additional demand.

Shortcuts

Fallen Order also has this idea of "shortcuts". When you do return somewhere you've already visited it is generally not to proceed to some previously unlocked door (as in Outcast), it is to make repeat visits to the same worlds less arduous. As you explore a world, you increasingly find the levels are a network of secret tunnels. It makes it simple to get back to any place in the world without having to perform the same feats of strength over and over.

This makes it possible to complete a linear challenge (say exploring an underground temple, or navigating an icy cavern) and then return back to your ship and go to a different planet. As you complete parts of the world, that part of the world becomes more open and non-linear and less game-like.

Rest

Throughout the map there are checkpoints, but you have to manually opt in to them. These checkpoints are little circles on the ground where you can meditate, upgrade your force powers and "rest".

The "rest" mechanic allows you to replenish your health and stim packs but at the same time re-spawns all enemies. That second part is interesting on a few levels. The first is the implicit encouragement not to take the safe path, to continue on without healing, lest you face the same enemies you've already beaten.

Ironically this makes a game feel less like a grind. When you can safely heal with no consequences, there is no reason not to do so. A player will usually pick the optimal path even if it isn't as fun. So as a designer you have to figure out ways to either make the optimal path the most fun, or penalize the optimal path in some way to encourage the player to actually participate in the challenge. And the penalizing can so often feel unfair or arbitrary. I think this trade-off strikes the right balance.

Secondly, it means our levels are rarely empty. They feel alive, like real places. Usually you have long dispatched all the enemies and simply walk lonely hallways trying to figure out how to get pass some arbitrary gate. At least in Fallen Order, the animals and the guards are continually reborn, and because of the aforementioned trade-off, that feels fair. Or the level is empty, but you are likely low on health so there is an element of peril which keeps things interesting.

Through shortcuts, rest, and ability based gating, Fallen Order manages to change the perceived shape of its levels as you play. And therefore the genre shifts between linear on rails adventure to open world brawler/rpg. But not just once, continually. They manage to pull this off without it feeling like an experimental porridge. They get to have the epic cinematic Star Wars set pieces we expect, without the feeling you are on a guided DisneyLand tour.