Non-linearity

The /idgames reviews for Jenesis Part 2 have started to come in and I'm very thankful for all the feedback so far. :D The linearity of my maps has been pointed out a couple times now, and looking back on them, I've decided that actually, they are somewhat linear, in the sense that there is very little leeway for varying your path through the maps - something I didn't quite take into account while making them. I'd like to learn from other mappers about the best way to combat my tendencies for unintentionally linear mapping.

Which maps out there are premier examples of non-linear gameplay in small-to-medium-sized space? :)

Map10 of doom2 is about as nonlinear as it gets, by my definition of the term. But it seems everyone has wildly varying concepts of non-linearity, as evidenced by a recent thread on the subject.

MAP19 (The Citadel) uses a neat trick: the exit is blocked by 3 sets of colored vertical bars, but you only need the red key and one of the others to make it past there.

You can even place your exit right at the start of the map, to make it clear what the conditions are. Then just place the keys on entirely separate paths in the level. The player gets to choose which paths, or he can clear the whole level if he wants 100% kills/secrets.

Gusta is the king of non-linearity. :)

Also check this thread: http://www.doomworld.com/vb/doom-general/54357-how-you-define-non-linearity/1/

you can easily achieve non-linearity in city maps by locking some buildings, putting keys in others and sticking "optional" weapons and items in the rest, but that's almost cheap. :) i mean what can you do... if it's small empty shacks (t.v.'s tvr! map03, doom2 map13, 16), it feels rather 90's-ish. if the buildings get larger and more complicated, it becomes harder to keep it logical without sacrificing the total non-linearity (doom2 map15, scythe map29). if you make everything sophisiticated, you will end up with a monster (plutonia, pl2, pl:rev map29s, cchest2 map15).
another way is designing the whole/most of the map as a sandbox, but locking the exit/final part with a few keys or switches (tvr! map25 or pl2 map18... the rest i can think of are larger maps like the final few in sod or scythe2).

you have to get really, really creative to achieve non-linearity without these "crutches", just by planning a goddamn good design. let's see... gusta's plutonia2 entries, especially map05 and map09 are strongly non-linear while smallish in size. t.v.'s tvr! map09 is even smaller and lets you pick your route as well. also agreed with vorpal on doom2 map10.

Without even changing the level design (or keys, etc.) at all, you can give the player more options by not crowding the starting areas with monsters (or providing some more power-ups), so the player can choose to run past them and tackle other areas first. Or you can offer him a teleporter or two to reach other areas.

Other ways you can give the player more options are to give him a health vs ammo efficiency decision. For instance, give him the option of provoking infighting so as to preserve ammo, but make the initial battles dangerous enough (and resources sufficiently scarse) that this may leave him with low health. Or offer a berserk pack right at the start. Then he can choose to use the berserk to fight with from the start, at the cost of squandering the health bonus effect. Or he can use more ammo, and then take the berserk to keep better health.

It's also nice if there is some potential reward for staying silent at the start - some monsters that only teleport in if you make a noise. Then the player can try running past everything, and only inviting the extra monsters in when it is to his advantage.

Extra route choices can be enhanced by making the map more free-flowing. Having to open a door while under fire can deplete a chunk of the player's health, so a gap in the wall rather than a door can increase the player's options.

I'm aware I'm only talking about the start of the map, but a different outcome from the start area will have a strong impact on how the rest of the map plays.

Anything that offers the player more choice in how to tackle the map reduces the linearity of the gameplay, even if the shortest route to the exit remains unique and unchanged.

Regarding the idea of showing the player the exit near the start of the map, and therefore hinting at what his options are to reach it: yes, this can be a nice idea, but be aware of the range of speedrunning tricks that can turn this into a way for the player to skip the rest of the map and exit in a few seconds.

Doom2 Map19 is indeed a very nice example. It's not just that the player can choose which keys to go for, but the routes to them are interlinked - it's not like three separate mini-maps, one for each key. Whichever keys you decide to go for, you still get to interact with most of the map, but the experience of them is quite different. (There's even an unintentional route option stemming from the fact that thanks to a glide only the red key is needed - but from a route optimization viewpoint, it isn't completely clear if skipping the blue key is worth it.)

In my eyes non-linearity heavily relies on the thing placement than the actual map structure. Don't ever give the player weapons and ammo before he proceeds to fight monsters. Make the player look for them. Consider the possibility of running into room with only a shotgun, few shells, and hoardes of huge monsters. Now the player has a dillemma and has to backtrack to search in unexplored areas and secrets for the resources to kill them.

In most linear maps, you enter each room with the resources you need to kill the monsters, then exit the room with even more resources, softening any battles that follow it. My best suggestions are to keep ammo and health in areas that the player would have to go out of his way for, instead of in plain sight. Doom 2 manages to capture this pretty seamlessly and would be the best maps to look at for ideas.

Nonlinearity maximizes replay value. If every replay of your map is nearly the same, then replaying is boring imo. A fairly narrow long path where you use the same 'hide behind a door' tactics or whatever tends to be linear. The main ingredient helping replay value in this way is probably the random movement of monsters. If you have places to go all around you full of non deaf enemies running around in nooks and crannies, then their random movement can put them in unique arrangements on each replay. This play, fight a cyberdemon near a crate, next time he happens to show up somewhere else, etc. Add randomness of all the other monsters and that's where a lot of the fun comes from because you're constantly playing by the moment with little ability to predict, which maximizes skill and fun.