The Psionic weapons, they are only available after you've researched/purchased/stolen Xeno Ethics and chosen Evil. These weapons are touted as great weapons since the damage they deal mid-way through the tech tree is near to the damage/space seen in the end of the tech tree. You do however pay for it in cost.

As for the types of weapons, I cannot say right now which is better at what. However I do know that each has it's pros and cons. Some take up more space, some cost more, some take longer to get to higher damage, some have the best damage in the end...etc.

The psionic weapons are evil techs from xeno ethics. The beam tends to be the best since its 12 damage, but it costs 150 per weapon. This is basically a game ender, especially on medium or below map sizes. Typically when I research xeno ethics and design a ship with psi beams, I'll fit 2 of them on a medium hull and top it off with an engine or 2 and some minimal amount of defense. On your average game that results in you cranking out a warship with 24 attack power, while your AI is still making small ships with attack powers ranging from 4 to 9. Hence the reason on smaller maps you clean up pretty fast since a few number of ships with psi beams go a LONG way zooming around the galaxy killing everything in its path.

I am under the possibly-mistaken impression TA changed the psionic weapons. Pretty sure when they were _really_ uber-weapons they were mid-tech, and yes they made it joyous to go evil. But now you need disruptors, which is now the last tech group before the ulitmate doom ray, to get the psionic beam. So it is only a (relative to before) slight advantage now.

Any of the ultimate tech weapons are better than the psionics, just used to be you could get to the psionic ones quicker. And nano-riuppers, which seem to be smoothed out now if I recall correctly.

Looking at the values I think the Nightmare Torpedo is better than the Doom Ray in damage/size but only slightly on a smaller hull. Generally missiles scale better if you plan to build larger hull ships. On the other hand I think they are a bit more economic strain to build. There is a difference in the research costs too.

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You can see all this laid out for you for DL/DA, with very nice graphs and analysis I might add (someone did a real nice job on that, my fav part of the wiki pages), in the wiki pages. For TA as said it seems to me it is somewhat different now. That said, such things as the pain of waiting for the missiles to hit on the battle screen maybe is more significant than the actual game play difference.

Personally, I'm a mass driver guy myself, as they seem to be the happy median between the power of missiles and the space-savers of the beam catagory. I don't like to go with beam weapons, because they seem to perform as little more than angry flashlights during actual battles. Too little money is on hand in the early game to justify the low space requirements.

I haven't played TA at all so for the big games in DA, I go for the Psionic Beam pretty quick, then ultimately go for the BHE which has the best ratio of size to attack. In the small games, I hit the beam line because it researches faster than the others. The line I research least is guns since it takes longer and doesn't provide weapons quite as powerful. In any case, if your game is big enough to afford the expense, it's fun to research two or even all the lines and confuse the AI by switching weapons fleet wide or by running ships with more than one type of weapon.

It's definitely true the best weapon is the one for which your enemy has no defense. However, in the big games, you can usually get enough military resources fully upgraded that it just doesn't matter. At that point, I usually load all my fighters with my weapon of choice without concern.

Agreed, they show up much later in the tech tree now and aren't worth expense anymore.

My weapon strategy is to research whatever type of weapons the AI isn't using, unless that would put me at a disadvantage against my current opponent's defenses. That way when I invade I'll steal decent techs from the other weapons branches and end up with good weapons from all 3 types without having to research the lower level techs.

So you are the guy who did that. Man, nice job. Best part of the whole Wiki hands down.

Also, once you start winning a war you will likely get advanced techs from somewhere down one or both of the other two weapon tech trees. Which means you will not have to research them or any techs preceding them (don't ever research weapon techs that have already been 'bypassed' unless you actually _want_ to build the lower tech weapon for some reason). So for instance you can research to Doom Ray yourself then go to war against a missile empire and steal Quantum torps or whatever and be only a couple techs away from Nightmare Torpedo having done absolutely no expensive missile research!

The tech and costs always seemed backwards to me. Seems like missiles should be _lowest_ research cost but highest cost (thinking re-supply here, so maybe maintenance would be more like it but you do not pay for actual weapon mount maintenance just for your ship hull, right?) to actually build, with beam the opposite and guns in the middle. But I guess that is my own mind's universe.

It does also take some amount of time for the AI to counter your first weapon choice. If you kill somebody off and do not just skirmish with them you will probably find you can get most of the way thru the war, even on a large map, without the AI having the ships out there adjusting until near the bitter end (maybe it is because I usually do not build warships until the war starts but set up to build them very quickly after it does - if the AI adjusts to your actual ships and not your tech ability it might never know until the war gets going and then faces a time lag, plus often it is also at war with another AI so has to split between defending against their weapons and defending against the player's weapons). It is sometimes the _next_ AI empire that poses the problem. Even then, if you are really loaded up the AI just never in my experience puts enough emphasis on defense to make a huge difference, preferring weight of numbers. But yeah it does make it a good idea, once you have reached the end of a weapons tech branch, to shift your tech down another line especially if you have a leg up due to some stolen techs from successful invasions.

Not sure wether or not it is economically best to retrofit your existing ships tho, someone might want to crunch those numbers. Sometimes when I hit that point I am well past where the AI can stop me militarily anymore. But I do not play on anything higher than 'tough'.

I understand that the type of defence you use does not matter. All defence types give the same protection from all weapons. Therfore 100 power ray sheilding provides 100 power stinger and mass driver protection as well. So it makes little difference which you use. It is better to use mass driver protection since the ultimate plating provides 10 units of protection and is the same size as ray sheilding that only provides 9 units of protection.

(Edit: reaction to LightVader, that darned CalifDude squeezed in between )

That's definitely not the case.
Always use the defense type that fits the enemies' weapon of choice.
Defense becomes significantly less effective (only the square root of the original value) when it's not paired against the enemies' weapon type. That'd make a 100 armor defense as effective as a 10 missile defense against missiles...

Yea, beam has the best bang for the buck. Regardless of anything else, beam is always where I start first.

Regarding defenses, I'm not one to do much mathematical analysis on the game like others have taken the time to do and then graciously share. I pretty much just go by feel. It seems to me, I get the best results by spreading all three defense types across the board. In other words, a typical huge hull fighter late game might have around 150 attack and 30 defense in each of the three defense types. Those ships seem to take more abuse than a ship with a particular defense type, even compared to defense against a specific weapon.

I'm pretty sure that defense is done as follows. If you have say 4/16/ 4 it ends up being the appropriated defense + the square root of the other two. So you in effect have 4 + 4 + 2/16 + 2 + 2/4 + 2 + 4 or 10/20/10. I thought I read somewhere that all 3 of your defense roll regardless. I know that there have been several times I've gone up against ships with 12 - 20 attack and my defenses were only around 4 - 9 in each category but I didn't ever take any damage. If I was 9 across the boards vs an attack of 20 over 4 - 5 rounds of combat I should take some damage if it only rolls 1 def. But if it does what I think, I'm actually running with 15 def across the board and the probability of me not taking any damage goes up significantly. This is why those spread defense ships seem to last longer. Though the effects of the defensive spread get weaker as defense gets stronger. My 9 across the board becomes a 15 across the board so I'm gaining 6 and probably taking up less space and spending less money to get any categorty to 15. But with 30 across the board since I'm not sure how it deal with decimals and the root of 30 is roughly 5.48 you are looking at more like 40 - 42 across the board. In that case if you know the oppenent has beens you probably better doing something like a 50/16/16 which gets you 58 vs beams and 25 or so vs the other stuff. The space/cost trade offs of defense if it works like I think can be modeled but gets more complex. Oh and since the root of 1 is 1 it's almost always cheaper to get one more def of the type you like by adding 1 def of another type. It also makes a 1/1/1 really be a 3/3/3 and is very powerful if you clash early game (or slow tech rates).

Though if I'm wrong (I haven't been playing long) then well I just wasted a lot of space.

Also, I read somewhere that you only get multiple defense rolls, ie one for each defense type, when attacked by multiple weapon classes --- though it is my observation (DL I dunno / DA I think / TA yes) that since _weapon mounts_ are fired separately you only ever get one roll anyhow. Then you have to consider the defense reductions... all this only applies for the _first_ attack in which that defense is used in a particular combat round. Also, fractions round down of course when you take the square roots.

probably boils down to the same thing Itzok says above, so... "what he said" (he is kinda the acknowledged combat math expert)