Sol Survivor/Survival

Survival Mode
Survival mode is all about defending for as long as possible, but eventually you will be overrun! You can play with up to 3 friends. Some players have scored up to an hour and 30 minutes - but an hour is perhaps a more realistic target to set yourself. The main difficulty spikes in survival tend to occur at 20-25 minutes, 40 minutes and 60 minutes. The spike at 20 minutes happens when the first "leader" creeps start to appear, and your setup will face its first major test. Assuming you survive that in good shape, you can continue adding to your defence, and will hopefully be reasonably comfortable for another 20 minutes or so. At this point, the creeps are getting a lot tougher and faster, and any deficencies in your defence will be shown up. Generally as long as you have a good mix of turrets and plenty of utility turrets this can be rode out. At about an hour the difficulty takes a massive uphill spike, and it becomes extremely difficult to survive any longer due to the sheer speed and toughness of the leader creeps.

A quick note on support powers - as the game progresses even the levelled up damage support strikes (e.g. Firestorm, Nuke etc) become increasingly ineffective. If possible take both rage and overdrive as your turrets can inflict massively more damage at this point.

Turret types:
There are several ways to breakdown how the turrets work, but the first is what kind of damage they inflict:

Electrical: (Blue)

Do equal damage to all creep types, have a slowing effect.

Piercing: (Yellow)

Do extra damage to mechanical, but less to cybernetic.

Heat: (Red)

Do extra damage to biological, but less to mechanical.

Concussive: (Orange)

Do extra damage to cybernetic, but less to biological.

Utility: (Green)

Do equal damage to all types, but are weak, and have an extra effect.

For this reason, you usually want a good mix of all damage types and to try and balance how number/quality of each. Different turrets also do either single target or area of effect damage. Generally area of effect attacks are weaker, but hit multiple targets, while single shot do more damage but only against one target. You need a good mix of both, but in order to get further into survival mode, single target turrets become more important against the leader creeps. Some turrets also have an additional slowing effect, and these are very important as time passes. Balanced against this, these turrets tend to do less damage overall.

Boost turrets are also increasingly important in survival mode, as they improve the damage causing capability of surrounding turrets. These effects "stack" so that a turret next to more than one boost will get the full effect of all boosts present.

Utility Turrets:

Slow Goo:

Does a small amount of damage to ground units, but it's main effect is to slow them down. Good goo placement is vital for ensuring your other turrets get to inflict as much damage as possible. A good tactic on maps with multiple converging roads is to overstack one of them with goo (or other slow turrets) so that the waves are more split up when they arrive in your killzone.

Turbulence:

Same as goo, but only effects air units. As there tend to be fewer air creeps, turbulence is a little less important.

EMP:

Although is claims to be good against shielded opposition, but is actually pretty ineffective at taking down shields. It is good at slowing down mechanical and cybernetic ground units though, and should be used in a similar way to goo.

Inhibitor Tower:

Inhibitor towers have a variety of effects - they reveal cloaked units and also stop creeps from regenerating shields and health. However, inhibitor towers are only really worthwhile in co-op modes as they take up a valuable slot, and the reveal effect can be replicated using cheap flares. Only use them in single player if you struggle with micro-management.

Speed Boost:

Speed boosts are the best general purpose boost, as all non-utility turrents benefit greatly from their effect (+30% fire rate). Speed boost is recommended for "constant fire" weapons such as teslas, machine guns, anti-air, radiation, lasers, pillboxes and drones. However, it does work effectively on all the other damage turrets. Stack multiple speed boosts in a grid pattern for best effect.

Critical Boost:

Critical boosts are very effective on the slower firing turrets, but not great on the "constant fire" weapons mentioned above. They give a 25% chance per shot do a critical, and the damage added to "constant fire" weapons is very small compared to the slower firing turrets. Criticals work best with shotguns, lightning bolts, silos and railguns. They help mortars, missiles and cannons to a lesser degree.

Range Boost:

Range boosts are very useful in certain situations, but work best with area of effect weapons where they actually boost damage potential rather than just letting them fire further. The reason for this is that later on in a survival game, prettymuch all your turrents are firing constantly and the additional range is less effective than one of the other boosts. Aside from specific turrets on specific maps, range boosts generally help teslas, radiation, shotguns and machine guns the most. This is because these area of effect weapons will now hurt more creeps for longer with their extended range.

Power Station:

Power stations give you a boost to your power income, and your maximum power cap. Each power station allows you to store +5 power, and boosts your income. These are useful, but difficult to fit into your loadout in a single player game.

Piercing Turrets:

Shotguns:

Shotguns attack both ground and air creeps, and pack a heavy short range punch. They do damage to everything within their blast, making them a useful area of effect weapon. This is balanced by their short range, which tends to make them useful only on particular maps. Shotguns work best on the outside of a corner, where they can fire directly into a crowd of creeps as they approach and exit the corner. Boost priority: Critical, Range, Speed.

Cannons:

Cannons are cheap and well balanced turrets, attacking both ground and air creeps. They fire in bursts, letting them benefit from both speed and critical boosts. Cannons work best at medium range on the inside of a corner section. Boost priority: Critical or Speed.

Machineguns:

Machineguns are quite similar to shotguns, with slightly longer range but no anti-air capability. They fire a constant stream of fire rather than bursts, and have an area of effect at everything within their cone of fire. They work best in similar positions to shotguns, on the outside of a curve. Boost priority: Speed.

Pillboxes:

Pillboxes are actually one of the most damaging turrets in the game, once fully upgraded (~3000 damage per second at lvl 3). They have a fair range, and work best on the inside of corner sections in a similar way to cannons. They have no anti-air capabilities. Boost priority: Speed.

Railguns:

Railguns are slow firing, slow turning and have fair damage capabilities. They fire at both air and ground units and have good range. The big benefit of railguns in that they ignore enemy shields, bypassing them entirely. However, this is difficult to use in combination with other turrets which will damage the shields first and makes them hard to use effectively. Due to their slow turn speed, they work best on the outside corner of a curve where their turn time in minimised. Boost priority: Critical, Speed.

Anti-air:

Anti-air, as the name implies, does not attack ground units. It is the single most damaging turrets in the game (~3300 damage per second at lvl 3), and also does a small amount of splash damage. Generally hard to include in your line-up in single player, where turbulence is usually enough to stop air units. Boost priority: Speed.

Electrical Turrets:

Tesla Coils:

Teslas are very useful turrets, causing good damage and slow down against ground units within their short range. Teslas work well on levels with lots of thin roads and sharp corners where you can get the maximum use of their short range - they're much less effective on maps with wide roads. Boost priority: Range or Speed.

Lightning Bolt:

Very useful general purpose turrets, they have a long range and hit both ground and air units. Although they do good damage, the major benefit of lightning bolts is they do at least 50% slowdown on any units they hit, and they will deliberately try to shot units which aren't currently slowed by them. This makes them extremely useful against the leader creeps you'll encounter as the game progresses. Boost priority: Speed, Critical.

Heat Turrets:

Flamethrower:

Flamers a unique turret which only effects ground units, and only unshielded ones at that. Flamers set on fire any unshielded ground units and the major damage they cause is through this ongoing burning rather than their actual attack. Flamers are best used at the "front" of the map nearest the dropships, and you should spread them out so that the enemy is constantly on fire until it reaches your main killzone. As far as I know, the upgrade level of flamers doesn't have a major effect on the burn damage they do, and I don't think it's worth boosting them either. Please feel free to correct this if you know different.

Radiation:

Radiation turrets are very useful, as they damage all units within their area of effect, and also make creeps more vulnerable to damage from other turrets. Radiation works best in your main killzone where it will assist your other turrets, and on the inside of corners and loops where it will effect a large area. Boost priority: Speed or Range.

Lasers:

Lasers are well balanced, inflicting damage on both air and ground units. They work best on the inside of curves where they have units in range for as long as possible, although they will only shoot one target at a time so this is less important than for area of effect attacks. Boost priority: Speed.

Concussion Turrets:

Missiles:

Missiles are probably the best all round turret in the game, they combine good damage, range, anti-air, anti-ground, slow and area of effect. The slow effect and splash damage are quite small, but worthwhile. Fairly fast firing so gain slightly more from speed than critical boosts. Boost priority: Speed, Critical.

Mortars:

Mortars only effect ground units, but have good range, slow and area of effect capabilities. Mortars are excellent early on, but their low damage at level 3 and high cost tends to make them less useful as the game progresses. Boost priority: Critical, Speed.

Drones:

Drones are an interesting unit with good damage and the ability to follow units far out of their range. This makes it a little tricky to get the best out of drones as they don't keep their fire within your killzone, but they can weak units before they arrive and chase down any stragglers who make it through. Drones only need a unit to pass through their range in order to be triggered and follow the unit, so can be placed well back from roads with their range only brushing the middle. Boost priority: Speed.

Silos:

The silos all have a very similar usage, differing only in the kind of damage they inflict. Silos are difficult to get to grips with, their long range means you want to place them very carefully - ideally so they are only triggered to fire as creeps enter your killzone. As they are expensive, but can't be upgraded it's difficult to know how effective they are. Boost priority: Critical, Speed.