I played co-op for almost 2 hours with one of our kids. We made it to the ring level. Going through the gate there I got the same crash as my previous solo game got on level 2. I'll send the errors on Discord.
On the single player ship select screen, it would be nice if L1/R1 would switch between Overview and Stats. Currently to change them I had to move all the way to the left to the Back button, then press up. The Back button itself could use a bit of touch up, as it doesn't really match the rest of the UI, and more blends in.
The co-op split-screen ship select could use with showing what button to press to select your ship.
"Do people even read these?" Yes, sometimes.
Our first playthrough my partner ended up dying in the rotating rings of the first level. I died trying to learn how to tow them out. When I selected play again it let use interact some, but we were in the same spots, and the Defeat screen never went away. I was pressing several buttons as nothing initially seemed to work, so maybe I paused at the wrong time. I was able to press Start to pause and, after a couple tries, was able to use the controller to get down to go back to the main menu.
Game 2 went better. My partner chose the Carrier, and I stuck with the Tank. All of the enemies bunched up and focused on the fighters, leaving us to explore the level and destroy everything. I got a turret fabricator that gave me a nice beam weapon with decent damage and over 600 rate of fire. I then got lots of shields and damage boosts. I went over to join the fighting, and eventually we decided to go through the gate at almost 30 minutes on the in game clock. My partner did not fare as well as I did, and while they got a number of items, they were low power. On the next level they continued to have bad luck, and ended up being destroyed several times. I figured with how powerful I was that it would be a good time to try a throne, so I activated the Throne of Blood. The swarms of enemies were constant and large, which did make things a bit more challenging for my partner, though I was able to revive them each time. I found that I had a hard time activating the tow, as well as triggering some interactions.
I think the issue was FPS, and it was often below 20, and sometimes dipped as low as 11. We were playing on a 4K screen. I tried various settings, but even 1080p was often in the 20s with so many enemies on the screen, and it did look blurry. Next time we will try switching to windowed mode or fullscreen on a 1080p monitor. The visuals generally still moved decently, but the inputs seemed to not respond as well, and the popups indicating you could interact also did not always show as you passed by, even when trying to slow down for them. My system is not amazing, but not too weak either.
Here's the Godot stats in the terminal: Vulkan 1.4.354 - Forward+ - Using Device #0: AMD - AMD Radeon RX 6650 XT (RADV NAVI23). My CPU is AMD Ryzen 7 5800XT 8-Core & I have 64 GiB of RAM.
By the time we went through the last gate I had nearly 40k in shields, and over 1,500 HP. I was regenerating Energy from doing damage, allowing me to spam my Heavy Ability. A few good upgrades to start and it can really make the game.
I think the co-op mode is a great addition. Being able to revive your ally with towing to a repair point was an excellent choice. Without some way to revive a companion the game would not have been nearly as fun, and the towing mechanic fits the game well. The luck based nature of the game is a bit of an issue. On one hand, being co-op, when one is powerful, both benefit. On the other hand, I got really powerful from that 1 turret upgrade, and that helped me destroy a lot more stuff, even just from stray shots while dealing with enemies, getting even more upgrades and becoming even further ahead of my partner. The did take the Carrier, so were already a bit of a support role, and those fighters certainly helped us early on to get the initial upgrades, but as the gap between us widened, it was not as fun for them. While I was over 1,000 HP, they were still close to starting levels. It wasn't until the 3rd level they finally got a 200 HP boost, which still meant their combined HP and shields were less than half of just my HP, and by then I was over 10k shields, and might have already hit that near 40k point. I think you may want to add a bit of rubber-banding should one player get significantly ahead of the other to help boost the lower pone up and keep things feeling balanced and fun for all. You could balance the boost for the lower player with lower chances for the player who is already ahead. I'd say that a focus on survivability at least would be good. Make sure that the more buffed player doesn't need to always go "rescue" the one less lucky. We had no problem with helping each other out, but I know plenty of people would have an issue with one feeling burdened by needing to help the other, or the one needing the help feeling like a dead weight.
The split-screen does impact the view, but it didn't feel too bad. The scaling did impact the menus, and on less than 4K they were a bit blurry with the default being very blurred and some things being hard to read. There was some overlap on the lower resolutions as well, though some of that may be from the low res setting on a high res monitor.
Overall, I think my main takeaways are that there needs to be some optimizing for higher FPS in co-op, and adding a bit of rubber-banding to keep the players a bit closer in stats. That and the bug fixes. Great work! The co-op is an excellent feature for the game.