I've done some research to tried and avoid creating a topic that has already been suggested or modded, but would welcome any redirect to discussion that already exists for this idea, that I did not see! (Edits to trim extra words and adding template format).
TL;DR
My idea is for a Raid Planet once we see additional planets in Factorio 2.0 sometime in the (hopefully) not-so-distant future. By this I mean a planet in which a player cannot take up permanent residence, but where some extremely rare and valuable resources can be found.What ?
I imagine the player landing on this planet (likely the last one they will arrive at or explore) and getting a warning message. "This planet's fauna seems to evolve extremely rapidly in response to an outside aggressor, like a body's immune system purging a disease from its cells. You likely won't be able to stay here long."The first landing, the player will laugh it off, and run around to see what the planet has to offer. After a few minutes or so of quiet, the player comes across alien life. Scoffing, the players shoots the tiny biter pup. Instantly, the player is attacked by a swarm of biters out of nowhere. The player came with a standard kit rifle and ammo, however, and repels the attack. But over the next few minutes, the attack waves come with increasing size, evolution, and frequency, and the player starts to get worried. The rocket isn't fueled, so the player rushes back to the launchpad and begins to prep the rocket. Placing a few turrets to hold off the biters, they take some damage, but keep working, as the biters are quickly overwhelming the basic defenses. The instant the rocket is ready, the player hops in and presses the ignition, vaporizing the biters that were crawling up the launchpad. Now in the safety of space, the player wipes the sweat from their brow and breathes a sigh of relief.
Hopefully you can see where this is going! At this point, the player would make their preparations and return with the best gear available to them. From the instant they set down, they would move with purpose, setting up defenses and getting to work mining resources. Eventually, they would still get overrun, but it would take much longer, and they could launch with actual rewards back to the awaiting space platform.
Why ?
1. I have always liked the concept of "death world" but the slowness and risk of play means I rarely get more than a few hours or one play session in. In Death World runs, you have to allocate most of your production to weapons and ammo to keep up with the biter attacks, and eventually you get overrun by evolved biters since they advance much faster and you advance much slower than how the game is normally balanced. There is also a risk of losing the entire run because if I lose a huge portion of my base or die, and there is no save sufficiently in the past to start from (or the save is many hours old and I don't want to repeat the work) then the run is over. At best, now we have to play with the biter settings to find something balanced (a tricky task), or play much, much slower than is usually fun, which is fine, but I think a "Raid" planet solves some of these issues in a more organic way that inspires creative challenges. The player will never lose their entire run, as the rest of the inter-planetary factory will always be safe and run under normal "safe" conditions but you will always have a challenge to return to as much as you want and with a clear goal for completing the challenge and no frustration when you eventually lose. I usually play Death World when I'm bored of standard Factorio or want some variety and actual combat after running a late-game world for some time, and having to quit out and start a new world usually breaks my immersion / investment and I end up going to something else and taking a break from Factorio for a while (I often see devs talking about similar issues and the best way to keep a player motivated and having fun). I think this idea falls perfectly there in significantly changing the options to a player, come 200+ hours.2. This idea adds a significant amount of new challenge and "gameplay" to the game by adding essentially zero additional "complexity", because the "Raid" planet doesn't need anything new added to the game other than a new named planet location, placing some of the already present end game technology or resources on this planet for the player to gather, and messing with the balancing for the enemies a bit (this is at least my expectation as a programmer but I admit my ignorance when it comes to anything specific to Factorio). So I don't see an unreasonable amount of work, and I see an abundance of benefit.
2. The Raid planet could be implemented on an instance basis (i.e. a random map/seed could be generated each time the player lands on the planet), creating some more variation in Factorio runs. So each Raid could be fundamentally different and sometimes you could get different resources. I guess technically you could do it on a dedicated map and return to the same location each time, maybe even a few remnants of your previous base, but to me, if you are getting wiped it seems like a benefit to have a new chance at loading something different / unique. Then you also resolve the problem of running out of resources at one spawn location.
3. As I mentioned, you add a whole new part of the game with its own problems, yet Factorio players will already have the knowledge needed to tackle this challenge. There are no new systems to learn that the player wouldn't already have a grasp on, yet at the same time, you've now added extensive end-game playability and repeatability and content, that you can give a near unlimited challenge to without threatening a players entire save file. (You would, of course, adjust the autosave system to always keep the pre-landing save, even when expert or extreme late-game players can make a 4-6 hour run on the raid planet.)
4. You could combine this idea with quality in a variety of different ways, such as: getting higher quality equipment drops from loot during the raid, mining higher quality ore during the raid, and also combines with rocket inventory limits and throughput in a sense of: what do you import versus what do you hastily produce locally? What level of buildings and items are you willing to sacrifice (since you won't want to import anything you have to take back with you due to cargo space) to get the job done and to increase yield? What will you prioritize exporting? You can see how it early in the cycle (relatively early, I mean, as by this point, the player will already be spacefaring and have a generally strong backbone of production) a player could really boost his progress by sacrificing a ton of cheap, mass-produced, essentially garbage stockpile (turret spam with basic ammo, burner miners and coal for rapid setups, etc.) to quickly get hands on a small amount of valuable tech (high tier quality armor and weapons, quality ore, special unique ore, etc.) and REALLY incentivizes super-late-game players to go in with max quality setups to get a super long run where they can establish a steady stream of valuables back to their monstrosity of a factory. You can see that it also renders some early-game tech useful long after they would otherwise be obsolete.
Additional Considerations
1. There are a lot of ideas about new combat systems, enemies, etc. I love these ideas and hope that we get new FFF about what the devs have cooked up among the thousands of concepts out there. Like many other players, I think combat is one of the areas most in need of improvements, and hope to see changes for 2.0, however, my idea is not specific to a new enemy type / defense / weapon, etc. it could be implemented no matter how the combat system is changed.2. I'm sure the development cycle for the expansion is way too far along for something like this to come as a late addition / change to the expansion. So maybe this idea, if liked enough, becomes a future addition (likely a mod). But still wanted to throw it out there.
The Downsides
1. I can see not everyone liking this idea, or it being a chore. As Factorio players, most are probably adverse to losing large amounts of their factory, at least as we play now where biters don't pose a threat beyond the first few hours of gameplay or to novice players who get lulled into a false sense of security before suddenly evolving biters start ripping through their "this will certainly never fail" defensive line. Similar to some discussion around quality, even making this planet "optional" in the sense that it can only speed up your progress, and you can do everything normally / slower without setting foot on the planet at all, still feels bad to those players, as in, they aren't taking the optimal route to their goal because it isn't fun for them, slightly spoiling their experience. I will say, however, I would not be among these players (obviously) and would hope that the benefits outweigh this downside, as for most players this would add endgame life and something to compete for (time before fleeing) and that players could engage as much or little as they wanted to.2. I can also see this as a downside being fairly limited to late game. It would be entirely possible for players who restart early on or who aren't so invested in the game to reach 200+ hours in one save (but still have a few hundred hours overall throughout the years) to never experience this mode (by requiring space travel, you also limit to expansion players only, which incentivizes expansion purchasing but also weeds out some less-invested players at the start anyway--players who are more casual or play less won't feel like they aren't good enough to reach this content "It's for expansion nerds, not me" sort of thinking). But, I must add, that this idea really doesn't add much "content" directly, doesn't require new items or anything, so even players who haven't felt like they've really invested into "raiding" wouldn't feel like they were missing out, either.
Thanks for reading! Would appreciate feedback and evolution on the idea, even additional downsides. Hope to see how other players would feel about this idea!