Chassis Tier System

T0 would be the tadpole with its two little chassis

T1 could introduce (at least) two different classes, the tadpole could dock in:

• A walking mech | maybe with the tadpole as head making use of the tadpole chassis | trading vertical mobility and speed for extra protection and usable limbs | features only available for the mech e.g. mining in previous games
• An advanced submarine | maybe with the tadpole docking from the back as the central engine, making use of the tadpole chassis, the glass front opening and the seat sliding into the larger submarine | make it just big enough so the player can stand up inside it and store a few things inside, maybe have a mono battery charger, dedicated fridge for 2 water bottles and a food item, a small common storage box and a micro fabricator, minimalism, like a mobile micro shelter, aswell it should be faster than the tadpole for superior exploration speed, but just much more protected
• Two archetypes of exploration, each again coming with some type of T1 “chassis” akin to the tadpole chassis and/or maybe as different models e.g. different T1 Submarines or Mechs

T2 could introcude two further archetypes on the next scale that each T1 vehicle can dock into (with very steep building costs and its own upgrades of course)

• The Transporter | with two T1 submarine slots and a T1 mech slot and the Transporter itself having a seat aswell so we support 4 people each with a vehicle. | The transporter would charge docked vehicles, come with installed storage boxes, a mini garden, a navigational device for planning together or alone, and would again allow player movement inside, while maybe one of the players drives the transporter, the others can repair their vehicles, hang out a at a glass front and watch the scenery, exercise inventory management. Of course the transporter would be fairly robust, just as fast as the tadpole if not slightly slower, and come with defense upgrades against small leviathans.
• The Boat | a floating vehicle with 4 omni slots each fitting any T0 or T1 vehicle | it has two modes: it can move on the surface (with swimming speed) or dive straight down (with a bottom camera), essentialy a massive mobile elevator to deploy into deep territories. | It would be extremely durable and allow for safe descent in some of the worst areas to come, at the cost of movementspeed of course. It could again feature some storage space, solar charging, open its roof while not submerged and double as a leisure spot during good weather aswell as support a range of minigames, while enjoying the above water scenary before submerging back into the horrors of the depth. | If the T2 Transporter was built aswell i coyld also attach to the bottom and add its speed to the Boat leading to extra fast ascend and descend or fast movement sideways movement while not submerged.

I would love to go further into Tier 3, but I would like to hold back on that, considering that the scope is already fairly large