Here is a list of my ideas for upgrading the game:

*New misc: Acidthrone. Used by the syringe it can vaporize the corpse of a human in 15 seconds. Lasts 60 seconds and has 4 uses. Crafting: 1x Chlorine, 1x Hyperzine, 1x Morbusine.

*New quest: "Cleanup". The player has to use acidthrone to vaporize corpses of enemies left behind by various reasons. In the Cargo spawnoint a crate spawns filled with acidthrone. Leaving the corpses of enemies killed by the player or other reasons in this mission or even humans corpses results in failure. All corpses located in the ruins, abyss and inside submarine's hull can be skipped. Also the remain acidthrone from the crate that was unused must be returned to the crate or replaced with other acidthrone owned by the player.

*Hyperzine effect can still stack, but will result in player losing health.

*Monsters cannot spawn 200 meters from submarine's spawn points (300 meters in combat mission mode).

*Assistants spawns with beefy equipment.

*Shuttles now spawns items out of the cabinets when used as respawn transport.

*Battery recharge dock has increased capacity to 8 (since 4 is just 1 more than 3 compared to batteries).

*Faraday artifact heals all monsters (except of husks as they are similar to humans) in the range of 50 meters for 10 health per second. It also can resurrect monsters if they're corpses were not teared apart in 60 seconds per 100 Health (crawler gets resurrected in 60 seconds when mantis needs 2 minutes).

*Carrier gets resurrected by Faraday artifact in 5 minutes, besides of having 1000 Health. Carrier will have than 500 Health.

*Stunned characters lose 2 oxygen per second.

*Ancient Weapon launched from a railgun deals more damage the more fuel it has left.

*Player using railgun controller to control a railgun or camera cannot use items he wields in hands unless double clicked.

*Sometimes corpses of enemies can be found around the ocean. Some are teared apart by railguns, other are having harpoon guns stick to them.

*More than one task can be done at once when visiting an area.

*"Beast From the Abyss" quest disallows player from making cargo missions in the area.

*Save file remembers killed enemies and does not resurrect them after repeating the quest (enemies may also as well be increased, just because they decide their defenses must be improved).

*Save files does not save the game if end round button in multiplayer was pressed.

*New quest: "Horror Under the Gate". The player has to kill all enemies in the range of 250 meters from the city (enemies can now spawn 200 meters close to the player's spawn point) or just fend them off the range of 250 meters from the spawn and let them remain out of it. Enemies located in the ruins can be skipped if they are fractal guardians. There will be more reward the more enemies are killed and the more dangerous they were.

*Charybdis and Moloch gives player 500 credits reward if they were not quest enemies at all.

*Endworm gives player 7000 credits reward after killing him if he was not "Beast From the Abyss" quest enemy. This may be explained by that Endworm was not posing threat high enough to deserve greater reward for killing him.

*New quest: "Just in Time". The player has to help repair a ship of A.I. controlled characters (putted into fixing leaks and fighting monsters). All damage must be fixed up, including devices like junction boxes to complete the task.

*Rewards for completing quests are not only fixed values, but they can also be for example 10% lesser than in earlier updates or higher. This is random.

*Shops are having limited amount of goods that can be bought.

*Colonies depending on their level of economy will offer greater rewards for making quests and more items in the shop (even items like incendium bar or ancient weapon). Prices are also various.

*A second crew orders panel in singleplayer that allows the player to set up automatically crew's tasks in the event of emergency siren being triggered and the same thing with alarm buzzer.

*Sometimes after completing a quest you will have to return the artifact to the city where you started from. The same thing is with killing monsters.

*"Beast From the Abyss" will be nicknamed as "Beast From the Abyss" by default in the campaign mode, after the media will start informing that it have destroyed already 2 submarines in a row, the monster will receive name "Endworm".

*That's right there will be news system.

*Save files remembers that specific quests got already completed and will not tell the player to start them over, after the save file is quit.

*You can skip the day and wait for new events to occur (remaining idle taxes the player for 200 credits for not being productive, however after the player kills endworm he can take a few free days from work without being taxed).

*When there are no active quests in the area, the player can take a day off receiving 100 credits for being available for the colony.

*Crew members including the player gets tired over by completing tasks and will have to take a day off (it will obviously result in tax).

*Hulls can have set in editor an beginning amount of oxygen quality and water level.

*Slots of the submarine's objects can be edited in the editor from 1 to 20. Oxygen generator can store up to 5 oxygen tanks and the player can increase it to 20. Medical box stores up to 20 items at once and player can reduce it to 10.


DIFFICULTY LEVELS FOR CAMPAIGN MODE:

Assistant:
Assistants are submarine's novice crew members, who graduated all exams to join, but still are too inexperienced to take on self a greater purpose on the board.

*Partly or fully used constant consumables will fully replenish upon the end of the task.

*Broken devices will be fixed up automatically upon beginning of the new task.

*Player is not taxed for deaths of the crew members.

*Players can change their professions in multiplayer mode.

Engineer:
Engineers are submarine's handlers with lack of resources and most damage done to the sub. They are responsible for the submarine's material loses, if they are not careful enough.

*Partly or fully used constant consumables will not replenish upon the end of the task.

*Broken devices will be fixed up automatically upon beginning of the new task, if there is a person on the board with enough skill level for that.

*Player is taxed for deaths of the crew members (in multiplayer all players can resurrect, but save owner will be taxed anyway, including his own death).

*Players cannot change their professions in multiplayer mode.

Captain:
Captains are national field officers serving as guide for a non-single minded crew, whose have to complete multiple dangerous tasks under the waters of Europa's ocean. Captains also sinks with their own submarines when they start drowning (because of tradition).

*All difficulty factors of Engineer difficulty, but players in multiplayer mode who died can no longer return to the campaign.

*Absolutely everything is saved.

*A.I. controlled crew members cannot have switched bodies with the player.

*In multiplayer player can see only where his character is facing. Rapid character rotating results in blur screen.

*Death of the player results in save file being deleted (there is an exception in multiplayer, that can be made).

*In multiplayer upon death of the save file owner, remain crew can get owner's ID card and become new save file owners. If they are more than one owner's ID card owners at once, random of them will become new save file owner. If A.I. controlled crew member has save file owner's ID card it will be ignored.


Permanent death rule and absolute saving rule will be forever disabled, if below conditions are made:

1.All colonies were reached by submarine.

2.Every kind of artifact was salvaged.

3.Every specie of monster was killed at least once.



Of course edit yourself my ideas as you like and you don't have o use them all.