I wanted to simulate ancient naval warfare and a very comon tactic called boarding. You all know it.
But most players in this game i guess, will rather think of aircraft on a carrier if it comes to sea battles to have some more tactical options like scramble or air battles or just for fun.

They wont think about 1-movement marine infantry on a galley who are boarding another ship after they exchanged missiles (air battle) before melee combat on board, while still be partially a land unit cabable to attack from ship to land and conquer ! it.

Look at this and imagine.

But there are 2 obstacles to think about:

A:

isAir units with only 1 movement are normally not allowed to attack a territory, because they need another movement to get back to base. But there is a simple solution called isKamikaze. To keep the Kamikaze alive, you have to use Triggers. More below.

As a important side note if you want scramble: Scramble does not need more than 1 movement nor isAir ! Scramble is magic !

B:

isAir units cannot attack a territory and stay there afterwards. The solution is called Trigger Attachment.
And it works like this (just set a condition always true)

<option name="when" value="before:NationBattle"/>
<option name="unitType" value="AncientMarines"/>
<option name="unitProperty" value="isAir" count="false"/>

and another one

<option name="when" value="after:NationEndTurn"/>
<option name="unitType" value="AncientMarines"/>
<option name="unitProperty" value="isAir" count="true"/>

The unit itself could look like this (scramble option not included):

<attachment name="unitAttachment" attachTo="AncientMarines" javaClass="games.strategy.triplea.attachments.UnitAttachment" type="unitType">
<option name="attack" value="1"/>
<option name="defense" value="1"/>
<option name="movement" value="1"/>
<option name="airAttack" value="1"/>
<option name="airDefense" value="1"/>
<option name="canAirBattle" value="true"/>
<option name="isKamikaze" value="true"/>
<option name="isAir" value="true"/>
<option name="carrierCost" value="1"/>
</attachment>

Now you have a 1-movement isAir unit able to conquer territory as a immortal kamikaze, because i turned it from isAir unit to a land unit just before battle and allowed it to stay alive because it only went isAir again after end turn.

Just imagine a land/air unit with only 1 movement, which is able to do all the following things:

1. Carried by a carrier (isAir, carrierCost) to participate in sea battles.

2. Air battles (airAttack, airDefense, canAirBattle) (isAir NOT needed !)

3. Scramble (canScramble, maxScrambleDistance, isAirBase (isAir NOT needed !)

4. Fake amphibious assaults (means without bombard, just from carrier to land)

5. Normal land attacks and conquest.

Finally lets look at the imperfection from the title:

I can now attack from land to a connected sea territory which i dont want to be possible, and this action will kill the kamikaze hybrid if i dont attack simultaniously with a carrier type sea unit.
So, its not perfect.
I must think more.

Thanks for reading.