3D game
First person view
The goal is to merge the feelings of wonder and terror that subnautica brings with the emergent chaos that barotrauma brings and wrapping up with the catharsis of success
The target would be a minimum of 10 hour of gameplay; potentially up to 30
Food/water should not form a focal point; medical play can be further established or simply left to a "miracle" cure

The players main goal will be to operate a submersible to reach the end. Visibility in general will be very limited with no windows looking out, visibility highly limited by light levels (the submersible will have a further penetrating light), navigation will be done using sonar with the player actively choosing between "active" and "passive" sonar. Active sonar will give a relatively large amount of info for the player to use to navigate but local fauna (aggresive entities) will be drawn by the noise. Passive sonar would provide much less fidelity and have a much shorter "range" but would not attract entities (fast moving entities should likely appear on passive sonar at the active sonar range).

Player

The player should control a person in first person view, moving through the sub using standard controls. When outside the sub (under water) the player should have more freedom and be able to move as you would expect underwater. This could include the use of devices such as scooters.

While underwater the player should have a limited supply of air to limit the time allowed without swapping tanks, or refilling the air supply. Tools should operate in a similar way with a scooter requiring a battery, a torch requires acetylene, etc.

Crew

The player would need to hire crew to complete other rolls on the sub. The player can only do one thing at a time. For Example:

The player can operate (drive) the sub
crew 1 can man weapon 1
crew 2 can man weapon 2
crew 3 can complete other auxiliary jobs

General commands can be given but AI crew should operate more or less with hands off of the player

Can the player swap control between crew members?

Multiplayer Extension

Multiplayer could let other people take control of crew members.

Roles

Two options here

Dedicated roles for each crew member
General crew members; everyone can do anything
Maybe add a levelling system; each role just gives a higher starting level but everyone can be a generalist?

Death and losing

If the player can swap control between crew members:

Crew that have died are gone forever

If the player is locked to a single avatar:

The avatar should respawn
AI crew should be dead permanatly
- New crew can be hired at outposts

The sub would be repairable if the situation can be salvaged; the player could continue their journey minus crew that had died.

Repair work should be free or near free when done by the player/crew.

If the player has determined they don't want to lose crew or the situation in untenable a revert should be an option.

Revert to the last save
- Latest manual save or;
- Latest auto save (every 10 minutes maybe? maybe only when out of combat)
Revert to last outpost Reverting should be a time penalty but all crew members that had died would be returned to their health at time the time of the save reverted to. Condition of sub would also be reverted.

Option 2?

Another possible method would be to spawn the player back in at the nearest outpost with a stock sub but this feels really punishing.

Maybe the original sub could remain as a wreck for the player to loot to make it less punishing
This could be potentially abuseable

Submarine

The submarine should be looked at as the player's mobile base.

Later iterations should involve different designs with a focus on a different part of the gameplay (attack, exploration, transport, etc) with tradeoffs between each category; initial prototyping should be a generic design. The submarine should be a base of operations for the player and have (nearly) everything the player needs to survive and navigate for gameplay sessions. This includes storage for ammo, dive suits, mobility devices, and tools. This should also include stations for use ship mounted weapons, sonar, and navigation.

Physics

The sub should experience buoyancy physics, with ballast tanks filling to sink, emptying to ascend, and finding a level where the sub is neutrally buoyant. The players should be neutrally buoyant when in the water and experience gravity when outside of the water.

Ballast

There should be compartments on the sub that fill with water to allow the operator to descend and to empty to allow them to fill.

Sinkable

The sub should be broken into segments that can be damaged by the environment and other entities. When the hull is damaged this should allow water in. This water would also act as ballast which could cause the sub to sink if enough water is taken on.

Repairable

Along the same vein as the sub is sinkable, it should also be repairable. This would allow the player to repair damage and allow a filled sub to be emptied of water.

Operation

The weapons operation should be operated at their own stations, while sonar and navigation should have its own station. This mean the player will have to recruit crew to operate stations that they are not currently using.

Modifiable

The sub should be modifiable to an extent. The player should be able to add items to the sub that can do basic logic operations (ie. Comparator, multiplication, division, constant output, etc) that can allow the player to modify the default operation of other devices. An example would be wiring a door to a motion sensor to allow the doors to open automatically when a player approaches.

Level Design

The world should consist of several zones (possibly 5?) with each zone being a more or less open world. The player would be free to travel anywhere they want in the zone for as long as they want (and have the supplies to keep travelling). Each zone should be sloping deeper except the last zone which should be more or less a flat roof. Zone 1 should be a simple straightforward zone. Zone 2 and 3 should consist of an upper and lower layer with caves/tunnels joining them. The size and freqency should be larger for zone 3 than zone 2. Zone 4 will be split into distinct halves; the first half should be like zone 3 with the caves joining the 2 regions increasing in size and frequency and the second part the barrier should be removed beween the two z ones. Zone 5 should just be a large cavern with the end goal located somewhere towards the centre of the zone at the bottom.

Progressing through the various zones, the difficulty should increase, and each zone should have unique generation paramters. For instance to increase the difficulty, the number of hostile entities could be increased, the hostility of the entities, the difficulty of the entities, and the terrain generation could make navigation more difficult. The terrain should also change uniquely; for instance, the starting zone should be relatively wide open with few obstacles. As the player progresses more obstacles could be generated, tunnels could become smaller, entities can hide in more blind spots, etc.

initial idea is perhaps a 2km x 2km map. This would likely represent the minimum.
- how many outposts would that include?
- might feel too small if not enough outposts

Outposts

Outposts should be considered more or less safe zones. You should be safe from the outside world while in an outpost allowing the player to relax and lower stress/fear levels. Outposts should be the location where cargo can be sold delivered or purchased, missions discovered, crew members added or removed, items purchased or sold, and any other admin duties that need to be completed. Certain sub interactions should also be available at outposts such as paying to repair, buy upgrades, buy modules, etc.

Outposts can be themed, to force the player to choose where to move onto next. This can be in ways such as wares are dependent on the theme, outposts can be run "factions", etc.

For players that don't wish to spend as much time moving exploring the world or harvesting resources to craft their own items, outposts would be the players main source of gathering items (ammo, weapons, fuel, etc.).

Points of Interest

Each zone can be filled with various points of interests for the player to discover if they desire. Examples of various points are:

Ruined/Sunken submersibles
Decrepit/Abandoned Outposts
Beacon stations (activate to get waypoints to further outposts?)
Resource Rich cave systems

This list can be further expanded at a later date if required to provide a rich and satisfying experience in each zone without the various points becoming dull to visit or being too spread out. These points could also become objectives to explore/find for missions.

Missions

Missions should be primarily a source of money.

Outpost missions

These are missions that can be received at every outpost. The list would be nearby outposts "requesting" something so the player does not have to return to the same outpost if they don't want to. Possible missions would be

transport crew between outposts
transport cargo
investigate a point of interest
recover resources The objectives for outpost missions shold be roughly on a path between the current outpost and the requesting outpost.

Zone missions

These are missions that should take the entire time, or nearly the entire time, a player is in the zone for. Moving onto the next zone should (may?) require completion of the zones missions I'm not sure what these missions should be yet.

Game Mission

This is likely a storyline point?

intra zone missions

Also a possibility. Will ponder further.

Crafting

A crafting system will be implemented. This would allow players to craft items that they require assuming they have the raw resources. This would be a different way for a player to acquire items that can be bought and potentially items not available in stores.

Deconstruction

Allow the players to deconstruct extra items to get raw resources.

Tiers

Items could have tiers? Food for thought.

Combat

Friendly fire would be allowed overall

Sub

The sub would have weapons controlled by a crew member. Ammo would be craftable and purchaseable. This could be combat between hostile entities such as creatures, or other subs (pirates?).

other subs can then be explored as a valuable but high risk source of refined resources to collect for personal use or sold for money to outposts
- guns
- ammo
- fuel
- components
materials can be harvested from entities that are required for crafting recipes or sold to outposts

Player

The player would have weapons available. These weapons could be crafted or purchased from outposts along with the ammo required. The player would have their own health, armor could be purchased or crafted to reduce damage from weapons or creatures at the cost of movementt speed.

Revisions

Maybe only use 3 zones but make each zone larger and more diverse