[TIPS] Endless Space Weapons and Defense Explanation

Combat in Endless Space doesn't give you a whole lot of information.  Stuff that you find online is sometimes outdated or wrong.  I'll try to provide general advice that will help you to build ships and win more battles against a surprisingly tough AI (and human opponents too!).

I'm sure everyone who has come here has already seen the wiki link here, but you should probably skim it first to understand some of my advice.

All advice is current as of December 28, 2013 for vanilla only.

Quick overview of concepts:

• Battle is composed of five "phases": Arrival, Long Range, Medium Range, Melee (Close Range), and Report.  Weapons are only fired in phases #2-4, so that's all I'll be discussing.
• Each phase has four "rounds" of combat.  In each round, kinetics and beam weapons fire once.  Missile weapons are fired on the second round of each phase and impact on the fourth round of the phase.  Thus, the missiles fired in LR#2 will actually hit on LR#4.
• Weapons fire simultaneously each round.

What weapons should I be building?

• At the very beginning, you only have access to kinetics, so obviously go with those.  However very soon you can branch out into missile or beam paths.
• Remember that missiles are most accurate at long range, beams at medium range, and kinetics at short range.  However, beam weapons are the clear winner when averaged across all ranges (e.g. they are the best "overall" weapon), followed by missiles.  Kinetics are ineffective until you reach close range, at which point they become devastating.
• Missiles are devastating long range weapons, but dramatically lose effectiveness as you get closer.  Against opponents without missile defenses and only kinetics (most of the early game), missiles are clearly the best weapons.  You can destroy entire fleets with first strikes and take barely any damage.
• Note that missiles have a "flight" time.  They fire on the second cycle of the phase and arrive on the fourth.  That means that a critically wounded ship that requires only one shot to kill it will get to fire for two extra cycles before your missiles destroy it, which wouldn't happen if you were using beam or kinetics.  However, this also guarantees that your missiles will be fired off even if your ships are destroyed immediately after, since they fire their whole payload at the start of the phase.
• Final note on missiles: since they all hit the same target in a phase, they're not very good against many smaller ships (a lot of damage is lost as "overkill").
• Beam weapons are best at medium range, but are good overall as well.  They're great for reliable damage output, and they should be your "default" weapon choice if you don't have a more specific plan.
• Kinetics are the riskiest of the weapon choices.  It is not uncommon to run into a battle and lose a kinetics fleet with barely any damage dealt (e.g. kinetics efficiency < 10%).  The most likely reason is that your ships are getting destroyed before they can get close enough to be accurate (kinetics have a mere 20% accuracy at long range).  However, at close range they can be devastating against an opponent who has insufficient protection, combined with the lower accuracy of other weapon types up close.  The trick is surviving until you can get close enough.

What's the general theory of defense?

• Note that fleet defenses are summed together when used for calculations.  For example, you can have one ship devoted just to deflection (vs. kinetics), one to shields (vs. beams) and one to flak (vs. missiles) and it'd be just as strong as the three ships with the defenses split among them.  However, note that if one of the ships dies earlier in the combat it opens a huge hole in your defenses, so I wouldn't suggest that plan.
• Generally, lean towards building weapon modules over defense modules.  Defense modules are useless if you "guess" wrong (e.g. you build ships with flak defense, but the enemy shows up with missiles), while weapons will always work at full effectiveness.
• The flip side is that if your enemy is heavily specialized (this can happen if one of their weapon techs jumps ahead of the others) you can build a counter fleet very quickly that can almost completely negate their damage.
• More simply:
• Balanced offense > Specialized defense > specialized weapons > balanced defense = balanced offense
• There's a lot more to combat than that (particularly the ranges of the weapons) but it's a good general rule of thumb.

What defense modules should I be building?

• First, an intro on defense mechanics:
• Flak defenses have a chance to shoot down up to three missiles per phase.  If interception is  > evasion, a missile is destroyed.  At all tiers, flak interception > missile evasion.
• Shields absorb a flat amount of beam damage per round. If you deal 100 beam damage and they have 50 shields, you deal 50 damage (excluding accuracy or critical hit factors). For perspective, the first beam weapon does 15 damage and the first shields absorb 15.  The final beam weapon does 200 and the final shields absorb 200.
• Deflectors absorb a certain number of projectiles per round.  Kinetic weapons are interesting- their per projectile damage increase is minimal (2.5 damage/shot at the earliest tech up to 7 at the end) but they dramatically increase the number of projectiles.  Tier 1 weapons fire only 4 shots per salvo, but the final tier fires 42.  For perspective T1 defense stops 2 projectiles and T10 stops 39.
• As a general rule for effectiveness: flak defense > shields > deflectors
• Or put another way: ratio of defense modules needed to absorb ~100% of enemy weapons of the same tier:
• Flak defense to missiles- 3:1
• Shields to beams- 1:1
• Deflectors to kinetics- 1.25:1
• Flak defense is the strongest in the game for its corresponding weapon type.  A relatively small number of flak defenses can destroy a significantly larger (up to 3x) missile amount. However, the defense is an all-or-nothing deal.  Either your flak will shoot down the missiles or they won't (potentially modified by battle cards).  If the enemy fires 50 missiles (evasion 10) at you and you have 10 flak defenses (interception 13), you will shoot down 30 missiles.  However, if they shoot 50 missiles (evasion 20) at you, you will intercept zero missiles.
• What this means is that as long as your flak defense tier is >= enemy missile tier, you should expect to shoot down 3x as many missiles as you have defenses.
• Flak that is higher than their missile tier is somewhat "wasted" since it won't be more effective, but it gives you more buffer in case of modifiers or if they upgrade when you aren't ready.
• It also means that if you are using missiles yourself, you should either aim to use MANY lower tier missiles, or get a higher tier of missiles than your opponent.
• Shield defense is straightforward.  It's a flat damage reduction per round, Of note is that if the enemy lacks the ability to exceed your shields in a given round, you will take no damage.  It also works well against lower tier weapons, but not disproportionately so.
• Deflectors are the toughest shields.  Superficially, they seem similar to shield defense.  They negate a certain number of projectiles per round.  However, the two key differences are: 
• At the same tier, deflectors are worse than kinetic weapons
• # of projectiles fired scale up very quickly with tiers
• This means that deflectors are decent against the same kinetic weapon tier, but terrible against higher tiers (but not as bad as missiles) because there are so many more projectiles that are totally ignored.
• Note that the converse is also true.  Higher tier deflectors are very effective against multiple lower tier kinetics.

Here's a chart to help summarize the defense concepts:

Defense Type	vs. Higher weapon tier	vs. Same weapon tier	vs. Lower weapon tier
Flak	Terrible	Outstanding	Great
Shields	Good	Good	Good
Deflectors	Poor	Okay	Good