There is a slight problem with the 0.0.11 Linux version. The game would not respond to level selection, making one get stuck in the menu.
Now, conceptual stuff, broken between six parts:
PART 1:
I would actually opt against the RNG. With hard stats, the game will feel more tactical. Tactics, in the end, is about predictability.
For the melee, I would rather skip it. In the tabletop WH40K, the mechanics for melee and shooting were different to one another - at least as far as I remember - and in the digital game, it would also take a handful of new stats to do for close combat. Meaning, it would consume energy in implementation and cause further rebalancing trouble, possibly turning everything unnecessarily more confusing.
Universal AP, responding equally for movement, shooting and use of special abilities, is okay, I think.
But mind that if having a heavy category gun costs penalty to default level of AP, it also means less shooting can be done with it. Therefore, such as you point out, big guns must have adequate punch, otherwise it will simply be unprofitable to hire them in the squad.
We could introduce character classes, such as:
Captain. The captain is a unique class, because it can only have one representative in the squad. The Captain has +1AP. Captain can only be equipped with with a light type weapon. Perhaps the Captain can also have +1HP.
There could be a Gunner. The Gunner can be equipped only with a heavy type weapon and in case there was a pick-up heavy weapon on the map - a treasure of sort - only the Gunner can go and wield it. Gunner has some penalty to AP, but since only Gunners can use heavy weapons - such as the Assault Cannon - maybe the shooting costs of heavy firearms, do not have to be as expensive.
There could be a Medic. Medic can be equipped only with a light type weapon and has -1AP. Medic has a special ability, granting a target unit on adjacent tile, a temporary +1HP (non-cumulative). The ability may only be used a limited amount of times per mission. If there is a pick-up medkit on the map, only the Medic may go and grab it, expanding his special ability in terms of the limit of use.
There could also be a Trooper. The trooper can be equipped with light or medium type weapons and has all the stats at default values.
For the weapons, a handful of ideas:
Light category:
Bolter Pistol: affordable, short range, single target, damage 2.
Storm Bolter: expensive, short range, multi target, damage 1.
Plasma Pistol: expensive, short range, single target, damage 4, low ammo storage.
Medium category:
Bolter Rifle: affordable, medium range, single target, damage 3.
Graviton Gun: expensive, medium range, single target, blast(friend or foe), damage 2.
Master Crafted Bolter Rifle: expensive, long range, single target, damage 4.
Heavy category:
Assault Cannon: affordable, medium range, multi target, damage 3.
Heavy Bolter: affordable, long range, single target, damage 6.
Plasma Cannon: expensive, medium range, single target, blast(friend or foe), damage 12, low ammo storage.
I assume the Marines on a 'space hulk' mission would not use any tank-destroyer armament or weapons that could get out of control easily.
For the enemy types, we would have the infantry of three categories and the bosses of three categories, matching the three infantry types. Perhaps more rarely some elite units could be seen, having higher HP values, but also being larger of size, if implementable, but that depends on the map grid precision.
EDIT:
Since blast on weapons can harm both the opponents, as well as the allies, I believe the HP system will need to be rebalanced, towards a universal approach.
PS.
Another thing, zoomability of the battle view. Important, I would say.
Also, what about being able to name each Marine as the player likes?
PART 2:
Having set the basic 'Bolter Rifle' damage at value 3 and the 'Bolter Pistol' damage at value 2, we must assume that the Rifle should be able to take out a 'Tier 1' Xeno in a single hit, while the Pistol, a 'Tier 2' Xeno in a single hit. Therefore, Xeno infantry, as proposed, by stats:
Tier 1; HP 3, damage 3, average rate of movement
Tier 2; HP 2, damage 3, faster rate of movement vs T.1
Tier 3; HP 4, damage 3, slower rate of movement vs T.1
Simple enough thusfar, I think.
Since Xeno infantry does 3 damage and it should be able to take out a Marine in a single hit, we must assume that a Space Marine has 3 HP, which is suggested further by own Marine armament efficiency comparison.
This is not all to it, though. Marines are heavy armoured and I would like to emphasize on that. If a Marine receives a damage to the front - that is, the damage comes from a direction the Marine faces - the damage is lowered by 1. Hit incoming from any other direction, that is either to the rear or to the flanks, inflicts damage in nominal volume. Which is why, rotational position does matter. The AI, if possible, should try to walk around and attack flank or rear if sufficient in AP, but not at the cost of possibility to attack given turn altogether, unless the nominal damage is too low to affect the target otherwise - which would mean, basic damage at 1.
When it comes to the HP bonus for the Captain, as well as that obtainable through special ability of a Medic, I believe we should double the bonus, making it +2 each.
When it comes to the 'low ammo storage' in description of plasma weapons, what I mean by that, is, these weapons need to reload each time having fired two times. In other terms, their ammo capacity equals 2.
When it comes to the amount of available reloads, I propose the nominal value of 9 for light type weapons, 12 for medium type weapons and 15 for heavy type weapons. We will see how it would do, whether it should suffice.
Some bigger maps and more open spaces, could be introduced, perhaps. Along with that, some more widespread battles. In such battles, the player would control a couple of squads, fighting a couple of different Xeno broods. The fight could go in such a way that, for example, squad 'A' begins, then brood '1' takes turn, then squad 'B', then brood '2', then squad 'C', then brood '3' and when all broods and squads are considered moved, the circle repeats. Each brood would hunt their squad of choice, unless some other squad - according to the AI calculations - is much closer or poses a bigger threat, then the priority may change. This could appear complicated, but the point is, instead of moving all the army at once each time, we take it by bits, more methodically.
Another thing, loosing a Captain, should equal 'game over'. While in majority of 'space hulk' missions, having only one squad in combat, it should be easy to determine who is the Captain, then what if there are more squads in action? In such case, there must be a priority squad, whose Captain, is the force commander, loosing of whom, equals 'game over'. It must be made clear what to protect and what to attack.
What still requires more detail is the 'blast' damage.
PART 3:
'Blast' damage could work in a way that taking a direct hit from a 'blast' weapon, deals 150% of the nominal damage, while all units on adjacent tiles, receive the basic nominal damage. All the damage is considered coming from one direction, that is, virtually in a straight line from the 'blast' gun of the attacker, for each case of damage dealt this way.
Ammo capacity of the guns - experimental values:
Light category:
Bolter Pistol: 5
Storm Bolter: 6
Plasma Pistol: 2
Medium category:
Bolter Rifle: 6
Graviton Gun: 4
Master Crafted Bolter Rifle: 3
Heavy category:
Assault Cannon: 6
Heavy Bolter: 5
Plasma Cannon: 2
For the 'price' of the guns, mentioned earlier, each squad would have own points balance and each unit armed with certain gun, would cost certain amount of points, subtracting from the total amount available. There is also a limit to the number of units that the squad can contain altogether. Captain is a mandatory unit and one granted for free, only the weapon cost needs to be covered in this case, while having a weapon equipped, is mandatory. This topic needs to be worked out carefully, but much later, I believe.
Further cases to be discussed: default AP of the Xeno, default AP of the Marine, AP cost of reloading per gun category, AP cost of shooting per gun category.
Part 4:
On the AP, we should begin with "currencies". First, rotation should be cheaper than movement for a Space Marine. Rotation should cost 1AP per ninety degrees turn, movement should cost 2AP per one tile.
Marine of reference - a Trooper class, armed with medium category weapon - should be able to move about three tiles distance per turn and either shoot twice or shoot and reload, ideally speaking.
Therefore, three tiles movement gives us already 6AP of minimum. What about the additional shooting, then?
Different categories of guns, have different priorities. Light type is not really the armament to carry the main weight of battle, as it is rather a mean of escape. Therefore, shooting would be costly for the light guns, but reloading, not as much. Heavy category guns, for the sake of balance, ought to be affordable in shooting, but since they already have some decent punch, perhaps it needs to be compensated somewhat with higher cost of reloading, as in the end, heavy guns are cumbersome in wielding. Medium category guns should be the way to go in lack of better idea for squad setup and not fall short against basic level of expectations.
Therefore, I hope these will do:
Light guns: 3AP to shoot, 1AP to reload
Medium guns: 2AP to shoot, 2AP to reload
Heavy guns: 1AP to shoot, 3AP to reload.
Summarizing, 6AP for exemplary movement plus two times 2AP for exemplary combat action, gives us the amount of 10AP, being a default for Marine Trooper.
All bonuses and penalties regarding the AP, likewise with the HP solution, should be doubled, meaning, the Captain comes with 12 AP right from the start, while the Medic, with 8 AP. Gunners, by the original assumption of -2AP - which, according to the current conditions, elevates to -4AP - are to come with only 6AP, that indeed is very little, so we will see whether this works out.
For the Xeno, they are omni-directional, which means - technically speaking - that a Xeno unit always faces all directions on the battlefield simultaneously. What it implies, is that they can move, as well as possibly attack, instantly any direction they want, without ever having to rotate. Xeno movement costs samewise as the Marine movement, while the Xeno attack, should cost about as much as their movement. To summarize, 10AP would suffice a Xeno infantry unit to move four tiles distance and attack once, if possible. That is for the 'Tier 1' Xeno. The 'Tier 2' Xeno has 12AP, while the 'Tier 3' Xeno has 8AP, to make it simple.
Xeno infantry can attack only opponents on adjacent tiles, but once they attack, they attack all the adjacent opponents, giving their attack a 'multi target' attribute.
EDIT:
What is still unclear, though, is whether two diagonally connected tiles, are to be considered "adjacent".
PS.
Shooting menu should have some "cancel" option.
I guess the Medic class does need some little further tweaks, as it may feel a bit useless for now, as well as there are some paradoxes if the extra HP granted by the Medic would disappear shortly.
Part 5:
Each square tile has only four adjacent tiles, that is North and South, East and West. Diagonally connected tiles are not to be considered "adjacent".
For the Medic, a redraw of characteristics. We remain with 8AP and default level of HP. The Medic may be equipped only with a light category weapon. For the special ability, now it has indefinite limit of use. The ability works on the basis of restoring the HP of a target Space Marine unit - other than the Medic himself - up to the nominal maximum, in case the unit was wounded. The cost of use in the ability is 1AP for each restored 1HP, which means, for example, if a target unit is being restored from 2/3 to 3/3 of total HP, the use of ability would cost 1AP, while from 1/3 to 3/3 of total HP, it would cost 2AP. In case the Medic does not have enough free AP to fully restore the HP of a target unit, partial restoration is available, up to the maximum free AP count of the Medic. The ability can only be applied to a unit on adjacent tile that the Medic faces.
There is also a bonus: if at least one Medic is present in the squad deployment, the Captain gets an automatic bonus of +1HP.
Part 6:
Having specified the notion of "adjacent" tiles, the 'blast' damage mechanics - correlated with the notion - would need some improvement. The improvement dwells in the way the adjacent tiles are affected by the impact. We still assume that direct hit from a 'blast' dealing weapon causes 150% of the nominal weapon damage. The adjacent tiles receive "just" the nominal value of weapon damage, but the direction of attack against these adjacent tiles, is now coming from the central tile, where the primary hit has landed. Therefore, dealing blast damage is now split between two steps. The first step is the direct attack, coming from the original attacker against the target of choice. The second step, is the attack coming from the primary target tile, simultaneously against the four tiles adjacent to it. This certainly affects the Space Marines, due to their rotary dependent armor bonus or lack of it, allowing for better result in damage infliction. 'Blast' damage specific to the second step of the attack, does not differentiate between friend or foe, affecting both alike.