The theme is ''attrition''. I want to know games where you can bunker up and wear your opponent down, ideally using periodic damage, i.e. Damage Over Time. It should be a potential playstyle in a game that gives you the freedom to spec into it, so it's not the dominant strategy. Can be real-time, turn-based, shooter, ARPG, whatever. As long as it's on GOG. Also welcoming any games that have a decent assortment of damage-over-time weapons/abilities.

I guess you could consider Heroes of Might and Magic games to fit into the category, where certain creatures and spells allows you to slow down, blind, turn into stone, or straight up poison your enemy, so there's plethora of that available - for example - in homam III's Fortress castle.

The only game I can think of is FTL. It's possible to build a ship based around ion weapons which disable ship systems. If you pull it off well enough it's possible to incapacitate most ships and also keep their oxygen generator off long enough that the crew dies. This will maximize the rewards you get from each encounter. Of course there are a few drone ships that don't have crew, and in the expansion/dlc there is an alien species that doesn't require oxygen. But most of your encounters should still be oxygen breathing aliens.
As you play the game you unlock several ships, and at least one of these starts off with ion weapons (the engi ship)

Here are some I've encountered:

Paper Sorcerer: Damage over Time abilities are often some of the better damaging attacks available. (Be aware that the game's difficulty curve is a bit strange; it starts out moderate, then gets easy, then gets difficult (and sometimes unfair) toward the end.) There's also healing over time as well, IIRC, though only as a higher level ability for one class.

Tangledeep: The Brigand gets a chance to cause bleeding when attacking, and have a couple skills that cause bleeding. Budoka get a passive that makes her normal attack have a chance of causing bleed. Spellshapers have a choice of invocation, one of which is a fire attack that also does damage over time. Also of note is that the most readily available healing methods (including the regen flask and most healing food items) are healing over time.

Lords of Xulima: There's bleeding, and I believe one of the magic elements (fire, I think?) is damage over time.

Daggerfall: Continuous damage is a very useful effect here, and the Regenerate Health (healing over time) effect is overpowered here. Morrowind and Oblivion also have damage over time set-ups, but they're not quite as good (but it might still be a viable strategy). Note that in Arena the Continuous Damage effect is broken, so that playstyle doesn't work well there. (You can't buy Daggerfall directly, but buying any other Bethesda game will get you Daggerfall for free.)

Wizardry 8 also has damage over time, but damage spells tend to be weak in that game. (The most useful spells of this sort are Toxic Cloud, which can cause status ailments as well as damage each round, and Death Cloud, which is instant death over time.) (I don't know how Wizardry 6 and 7 compare here, though I know they have damage over time spells.)

While not an easy way how to play the game, Terraria has dozens of different debuffs that certainly are capable defeating most of enemies. Combine it with expert mode and you get a real challenge!

Looking For. A common abbreviation in multiplayer game communities.

OK, thanks. Never been in one of those, so that may be why I didn't know it. : )

You mean, games where this is only an option?

In Morrowind Damage and Drain spells can be either instant or DoTs. Since you can make your own spells, the possibilities are nearly endless.

In Oblivion you can also create poisons for your weapons.

In StarCrawlers having a hacker in your party is always recommendable for various reasons. They also have most of the DoT abilities which can become incredibly powerful. Additionally there are several weapons with that effect (ie. setting your enemies aflame).

In Bioshock you have swarms which will damage the enemies - bees in BS1+2; crows in BS:I - these not only do DoT, they also distract the foes. Also some other weapons or plasmids/vigors have DoT effects (fire, electricity (+stun) etc...)

In Witcher 3 putting your points in the appropriate alchemy skills will give the weapon oils a chance of poisoning the target. Another level there will also increase your defence against the same target. Also weapon enhancements may apply effects like burning or poisoning on the enemies. Then there's the Signs - Igni might set enemies aflame of course, but the highest level Yrden not only slows them considerably but also damages them continuously. And then there are environmental effects you can use - bee hives, gas clouds, fire, depending on the situation.
I didn't especially skill for it but in my currently play-through in the later game I had many enemies die by DoT effects, and they were certainly a great help dealing with tough and high hp creatures too.

Actually, in Morrowind:
* *All* damage spells that you can create are damage over time; you can't create instant spells. You can enchant items with instant spells (just leave the duration of the effect unchanged), but you can't do that with spells.
* Drain doesn't work that way; it functions as temporary instantaneous damage. The stat will drop instantly when the spell hits, and will return to normal when the spell wears off (assuming the spell didn't drain the target's health to 0; if that were to happen, the target would die and not come back to life when the spell expires).

Oblivion is similar, except that there are pre-made spells that are instant, and you can't enchant items with cast on use spells, and custom cast on strikes effects can't be instant.

World of Warcraft (Classic) - roll a warlock or shadow priest

Technically true, although some prefer to make high-amount low-time spells which act like "instant".

You're right, thanks. Mixed that up with "Absorb ...". Vampiric spells ftw ;-)

It's been ages since I played it, but if it's like Skyrim then the spells aren't really fire-and-forget but rather channeled. Not quite what I want, or most any machinegun in any game would qualify. TES also punishes using heavy armor when casting spells and while there are defensive spells, they compete for magicka with destruction spells. So bleh. Yeah, that's probably the best non-RPG I could ask for when it comes to this. Fire/Frost arrows right out of the gate, with quite a bit more to look forward to in the mid-late game. I'll have to look at Starbound too.

Skyrim is actually diffgerent from previous games in the series when it comes to magic. In earlier games in the series, you just cast a spell once, and it has its effect, which can be a damage over time effect. So, you could create a long-lasting damage over time spell, cast it once on the enemy, and then just hide or run away until the spell wears off or the enemy dies.

The only TES game I am aware of that penalizes you for wearing heavy armor (or light armor, for that matter) while casting spells is Oblivion; I know that Daggerfall and Morrowind have no penalties at all for wearing armor and casting spells. (In Arena, casting spells in heavy armor is impossible because there is no class that can equip plate mail and cast spells; on the other hand, a powerful custim Shield spell does not wear off with time, and you can just rest after casting it to get your spell points back, but unfortunately the Continuous damage effect is broken in that game.)

Also, Morrowind and Oblivion allow you to place custom "Cast when Strikes" effects in your weapon. So, you could equip your magic weapon, hit an enemy, then run away or switch to another weapon while the enemy is taking damage; in Oblivion, armor won't interfere with this. Also, if looking at Oblivion, don't forget that you can use Alchemy to make custom poisons, which can do really nice damage if you're patient.

When talking about RTS you mean turtling. It is not that much about DoTs against the enemy but more about bunkering up and wearing down the enemy forces with defensive positions, until you can anihilate the enemy. Most of the time with strategic or other kind of super weapons.

Supreme Commander was about this playstyle when using strong defensive positions with big shields and big artillerie to wipe the enemy from the map.
We got the successor Total Anihilation on GoG, but I don't know how much that one is about being the turtle.
But you can do so in Ashes of Singularity. Buld up strong defensive positions, build up a group of heavy dreads (and let them level with shared XP from the defensive position) and in the end anhiliate the enemy.
No superweapons for killing the enemy without leaving the base though.

You can use a similar playstyle in Earth 2150 too. Turtle up and build a lot of nukes or other strategic weapons and bomb them back into stone age.
Perimeter is more or less about this too.