It is pointless to increase the difficulty of the game

[SoShootMe]

I also think achievement are useless for players, they do not increase the game difficulty, they document something that happened. I read devs use them to gauge what players are doing and which hurdle they are facing. So i wouldn't be surprise to see some new related to space, more like milestones.

I disagree that they are useless, they are just not about difficulty. Some of the Factorio achievements such as "Eco unfriendly" and "Getting on track" can, as you described, provide information to developers but many of these also serve as guidance for players in terms of progression.

I think some others also benefit players as a slightly different sort of guidance, that is even more useful. For example, I found "Lazy bastard" solidified the early game recipes in my mind and of course encouraged solving the problems to achieve full (and early) automation; "Getting on track like a pro" got me to figure out how to progress the early game much quicker (which feeds in to "No time for chitchat" and "There is no spoon") without being an overwhelming goal; and "Solaris" and "Steam all the way" encouraged me to investigate solar and nuclear power respectively, discover their challenges and resulting trade-offs, and decide for myself how I like to play. And more, but I think those are enough to make my point.

To bring this back to the original post: achievements for Death world etc would be somewhat similar to the above (especially "Solaris" and "Steam all the way") but on balance I think the distraction from the current focus on "Default settings" is a negative that outweighs what they would add. Perhaps more importantly, my impression is that Death world etc are not actually "game modes", but merely presets for the many settings, ie there is no concept of that selection once you start a game. That would mean such achievements might be difficult or impossible (at least currently) to define.

[Tertius]

I think some others also benefit players as a slightly different sort of guidance, that is even more useful. For example, I found "Lazy bastard" solidified the early game recipes in my mind and of course encouraged solving the problems to achieve full (and early) automation; "Getting on track like a pro" got me to figure out how to progress the early game much quicker (which feeds in to "No time for chitchat" and "There is no spoon") without being an overwhelming goal; and "Solaris" and "Steam all the way" encouraged me to investigate solar and nuclear power respectively, discover their challenges and resulting trade-offs, and decide for myself how I like to play. And more, but I think those are enough to make my point.

If used as a guide, these achievements have some use. However, the player has much freedom how to get there. At first, the speed achievements seem extraordinarily difficult up to impossible if you just use all default settings and start with some random seed. The most impact to speed are enemies.
But if you learn how to tweak map settings without disabling these achievements, they get vastly more easy. The speed achievements get disabled, if you change the enemy bases or activate peaceful mode, but by just setting the start area to maximum size you effectively avoid enemies within the area you will occupy while doing your playthrough. And disable enemy expansion and pollution, so they will neither expand into the starting area nor send attackers due to pollution. Additionally, increase the ore frequency and richness, so you don't need to really expand but just build your mines on the spot. Finally, disable cliffs, so there are no obstacles.
Then you preview the map and generate new seeds until the location of ores, oil and water is most convenient.

So the speedrun achievements are not that prestigious as they seem. They just tell you have organized yourself and prepared a number of useful blueprints to be used in the correct order.

[mmmPI]

I disagree that they are useless, they are just not about difficulty. Some of the Factorio achievements such as "Eco unfriendly" and "Getting on track" can, as you described, provide information to developers but many of these also serve as guidance for players in terms of progression.

I thought of the badge rather than the stated written objective. I see your point that it can serve as guidance, incentive to automation or warning with the pollution or forest fire.

I think some of them may be difficult to get, but they do not increase the difficulty of the game, they provide a list of challenge that do not depend on the player. Maybe this formulation is better than my previous attempt, because some of them are somewhat related to difficulty in my mind.

I can see "beat the game in deathworld" as an achievement, or "in marathon". But then you just got to pick the proper seed or join someone's else game... There could also be something like "destroy X nest in 10 minutes" (conqueror) or "have your defense repeal X behemoth in Y minutes" (defender) that would not depend on particular starting settings and also incentive a similar playstyle where difficulty is measured in terms of combat but that kinda feel wrong to me, considering the engineer crashed on a planet and trying to leave it, eradicating all lifeform on such planet would surely be a challenge, but not sure it's worth a medal x).