I should start this review off by saying I've never been a huge fan of the Metroid series. For some reason the games just didn't really click with me in the way I had hoped. I guess maybe it felt a bit too slow paced for me in the early game and it somewhat turned me off.
With that said though... holy shit! From start to finish, this mod is an absolute marvel to behold. I've always been a HUGE fan of mods that manage to completely remix the way a game is played while still working with the conventions of the original design, and this does it in spades.
The exploratory ethos of Metroid gameplay merges very well with Sonic Robo Blast 2's level design, and the implementation here also solves my issue with Metroid games being a bit too slow paced for me. Upgrades come fast if you go out of your way to look for each item box and it becomes an incredibly rewarding experience to get super powered early on and be able to blaze through levels with ease in the lategame.
On top of that, my preferred way to play through SRB2 is co-op with friends, and this mod has absolutely wonderful support for it! There are many settings you can choose to tailor fit the experience to what you and your friends want, including changing the spawn behavior for item boxes, limiting it to fresh saves so everyone is on an even playing field, and a wealth of other options. I am extremely happy to see my favorite way of playing this game so fully supported!
One comment I will make is that me and my group of about 8 friends experienced a lot of lag at one point in the Samus exclusive area in DSZ. It got so bad that most people dropped to 1 frame per second! We had to use the exitlevel command to skip to the next level. Trying to avoid spoilers where I can, but three of us moved on to the encounter in that level while 5 of the others were still working on the platforming section, and our running theory is that the game had a lot of trouble handling that many people spread out across the map, as when we went back to it again in a later session it was fixed by simply waiting for everyone to catch up and sticking together before entering the encounter. I feel like this might be more a limitation of SRB2 netgames rather than the mod itself, so I will not be deducting any points, especially since there's a simple fix.
Overall, I was impressed with this mod, and I can say without a doubt that it's one of the absolute best I've seen in my ten year tenure of playing SRB2 and lurking the MB. (just look at my join date!) As someone who really loved SMS back in the day, it makes me extremely happy to see that you're still around and making cool things for the community, and I will continue to keep a close eye on the content you produce. Thank you!
-First, try to start in OpenGL and close any programs, see if it works in a few tries.
-If that doesn't do it, rename sav1.dat to sav2 or sav3. That moves the save slot so nothing will be loaded at first and SRB2 gets more time to initialize. You'll find that file in "Luafiles>Client>MetroidVanguard"
I'll probably try to make another patch in the future to try mitigate SRB2's I/O limitations. Sorry for the trouble!