Here are a few ideas for some additional terrain and object types to add to Rivals Masters of the Deep board game AND tabletop wargame. In general, I think going a universal route (cross factions) first would be best for simplicity's sake when trying to create new objects in the terrain. The factions could have their own styles, but the same effects would speed play testing and simplify rules. Please provide feedback and any other ideas you have.
First, a healing source providing an area effect healing status. A single healing source would be used by all factions in this case aether (think bacta from a galaxy far far away). (A different “healing” source may be needed for automatons, like a repair swarm.) Each faction could have their own style, but the action would be the same. There would be a healing area effect of 1-2 health a turn within a fathom. The negatives would be reduced offense (due to disorientation?) and maybe reduced defense as well). The healing source would be relatively fragile, so could be targeted and destroyed or destroyed by grenades/mortars.
Second, bunkers could be made in a bolted steel style for Cog and dug out coral and rock for the other factions. The bunkers could have any number of firing portals. I would see the bunkers require movement to enter or exit. They would provide a defensive boost, but limit direction of fire to templates from the firing portals (board game could limit to a wedge). I would see protection from mortars, but grenades doing double damage and causing a stun if successful. You could fit 3 small units in a bunker or 1 large unit.
Trenches could be a similar option to bunkers for defensive oriented games. There could be games designed where a small force has to prevent an attack by a much larger force. The defender could be allowed to determine their defensive layout. The attacking force would have to strategize an attack.
A turret could have different designs for different factions. Crossbow/ballista, cannon, mortar, some aether powered energy weapon are a few possible types. The turret would provide good damage and range buffs but have vulnerable external tanks. As a result they would have low life and explode when destroyed causing high area effect damage (to the unit using the turret as well as other nearby units).
The hydro vent concept mentioned by another Kickstarter could be a power source for a powerful object an attacking force is trying to destroy or some other powerful object that could turn the tide of battle. Either something like a weapon (artillery piece or cannon) or something that controls the tides and allows the controller to use the tide each turn to shape the battle. Multiple power sources could make a fun objective based scenario (damaging sources could impact the powered objects effectiveness). They could also power turrets, though I like the idea of turrets having their own power source that would explode, causing area effect damage, when destroyed.
Kelp forests would be a great linear obstacle that would block line of fire from units outside of it. Units inside the kelp would get a defensive bonus and a movement reduction. It would act as concealment.
Other items like barrels (explode when damaged), mine fields, and kelp forests (concealment, so reduced movement but harder to hit) could diversify the terrain and strategy options.