THIS IS AWESOME! ...and brutally difficult to advance, even on 'Casual'. Could you drop the game speed to 0.025 when the inventory is open, to give players more time to decide what options to choose? Perhaps even allow them to set up a handcrafting queue where each item will automatically trigger as the funds become available?

Also, here is a Reddit post that might give you some more ideas: https://www.reddit.com/r/factorio/comments/18jjk1m/factorio_survivors/

Oh that's amazing, thanks for the reddit link, I love that idea. I think it could be very fun to have to manage science and defend the labs, perhaps I can find a way to add some of those ideas in, or even add a second scenario map to the mod :)

As for the difficulty, I'm very glad to hear feedback. I intended the game to be somewhat challenging, but more than that I want it to be fun! And I agree that for some reason it's currently very difficult even on the easier difficulty modes. I like the idea of changing the game speed while inventory is open, however that becomes difficult when it's being played in multiplayer because I wouldn't want the game "randomly" slowing down for everyone when one player opens their inventory. For now I am considering making the enemies a bit slower, so it's more like Vampire Survivors where you can mostly run away from stuff when you're feeling overwhelmed. Perhaps that could also be paired with a buff to the run speed upgrade.

I am also considering giving the character more resistance to acid damage. Getting trapped in the spit kills most of my runs, so I'm considering something to mitigate some amount of acid damage as well.

I love the idea of a handcrafting auto-queue. I've never made something like that before, so I'll have to think about how to add it in a good way. I also have a similar-ish idea on the todo list, where I'm hoping to make a little recipe/crafting shortcut GUI that you can pin to stay open at the side of the screen for quick access to all the upgrade recipes. Adding an auto crafting option to that GUI seems like a good idea.

Glad to be of help. Some more thoughts:

1. There is another rogue-like mod: https://mods.factorio.com/mod/roguef / https://github.com/ZwerOxotnik/m-roguef/ / https://mods.factorio.com/mod/roguef-weapons

2. Killing mobs in the lobby generates coins which transfer into the game. I'm going to call that a bug. Also, it seems like mobs die and drop coics in the arena while you are in the lobby. It might be a good idea to have a 'drop_coins' multiplier for dropped coins that is set to zero so mobs don't drop any in the lobby OR the arena while the player is in the lobby.

3. Perhaps the multiplayer-friendly option for the open inventory is to have the mobs lose lock on the player and the player be unable to move or take damage while it is open. That should make for a good enough substitute for pausing.

4. A 'dodge chance' buff would be VERY welcome. Incomberance should be an issue that affects it. i.e. It should be 0% with no armour and 95%(?) with the heaviest armour. Player speed should also be a factor in the chance to dodge.

5. For 'meta progression', perhaps players could keep a small percentage of their cash and even save it in a chest in the lobby, with their buffs only being removed at death, rather than also while transferring to the arena. That will allow players to get started setting themselves up before they enter the arena. One (expensive!) buff should be to increase the percentage saved for that run.

6. I would have both automatic and manual weapons (pistol/shotgun/etc.) and have the player have to buy ammo for the manual ones. They could start out with the pistol and 10 regular mags to help deal with leaks.

Cheers!

The coins dropped by the lobby test dummies are intentional :) You can even use the /gamble command to test your luck and potentially enter the arena with enough coins to immediately buy a couple upgrades (you can also use the /gamble command while you're in the arena if you're feeling brave enough! hehe)
When you return to the lobby, all the enemies left in the arena are deleted (without dropping any coins), but all the coins dropped by player kills remain. This is also intentional; to make your future runs a bit easier, if you die you can go back to your body and retrieve them in the next run. I think this is a sort of similar mechanic to your meta-progression bulletpoint, but I realize it's not really communicated anywhere or clear what's going on there.
I've been thinking about adding a dodge chance, so I'm glad you suggest it. I didn't add it originally because I was worried there were already starting to be too many upgrades and things to think about and manage. Similarly, I haven't been quite sure how to integrate manual weapons, but I do think it would be nice to have them, even if they're mostly only useful for the beginning. And since now there's some interest, I feel much more motivated to figure it out and get them added! I'm curious what you think about just giving the player an SMG at the start, and being able to use coins as ammo for it?
I appreciate all the feedback and ideas, this is great, thank you! Lots to think about