Interesting game, though I don't know if I actually finished it or if I just don't know how to progress further.

Anyway first the good things:

So, I love those recordings and the robotic voices suit the vending machines. I wish there was a bit more of that, it certainly gave the game something special.

Mapping is also pretty good, it uses mostly MV RTP, but you did manage to use it in a good way and the locations feel distinct and have their own atmosphere.

Now, for the things that could use improvement. While there's a lot, don't let that discourage you. For a first RPG Maker game, it's pretty solid and certainly stands out. But here are the problems I've noticed:

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There's a chest that has the key to the House of Parliament. The chest get activated on player touch, which is fine, but it gets activated everytime you touch it and always gives you a key. Even after you already have it. You should put a switch there to make sure it activates only once and that the player only gets one key from the chest.

The game has a problem where certain areas don't have clear exit. You should mark the entrance/exit tile in the area. Maybe just put a carpet there or something to mark the tile that transfers you to another map.

Another thing, this game uses the sideview battle system, but all the enemies on the battle screen are aligned as if it were a front-view battle system. Just put them to the side. Also, some battleback would be nice, even some of those default RTP ones.

The main character is literally named Main Char. Either let the player name him with Input Player Name, give him some default name like Brian or even call him something like SCP Agent. Main Char as a name doesn't work in a game you are supposed to take seriously.

There are also some tile passability issues where you can walk on walls in certain places.

I don't think the random encounters really work in this game as they are right now. It would've been better if the random map encounters were replaced with wandering enemies that trigger an encounter if you run into them. Or have certain regions that can spawn random encounters. Also, the random encounter rate seemed a bit too high for me, but with randomness, it's always difficult to tell.

Combat balance... well, that the common wretch is much stronger than the rare Street Sweeper, despite the latter offering much greater rewards. The common wretch is also way too strong. I think the stats of these two enemies should be switched. Also, the Double Attack skill has no effect when used.

There's a cave entrance in the basement of the House of Parliament, but you can't interact with it, so I don't know if this is a bugged transfer event or if it's just for decoration.

The ending confused me, in the way that I'm not actually sure if it even is an ending. You meet an old man who wants you to get him some Crystal from a vending machine. You can agree or refuse, but he will always instruct you to get the Crystal, albeit with slightly different wording. Afterwards, you have no other option it seems then to do as he asks. Once you come back to him with the Crystal, you have the option to give him the crystal or no. If you choose no, nothing happens and you can talk to him again and make the same choice. If you give him the Crystal, there's some more dialogue about the MC transforming into something else and then a Game Over screen, making the player think they just got a non-standard game over.

If giving the guy the Crystal is supposed to be the actual ending of the game, use the Return to the Title Screen event command, otherwise people will assume they made the wrong choice and weren't supposed to do that. If the Crystal thing was supposed to be the ending, then also make it a bit longer. Maybe we see the MC's actual transformation, maybe there's a scene where more SCP agents come in to investigate, only to get killed by transformed MC. Just some ideas.

There's also not really any music or background sound effects (well, apart from the battle music, which I don't think that particular RTP track really fits). It makes the game feel very silent, but not in a creepy, eerie way, but in a "this game is unfinished" way. Even if you want to stick to RTP assets for now, something like MV's Dungeon 6 would've been nice to hear on the map. Or have footstep noises for the main character. Or some background sound effects. Something so that the game isn't so silent. Though I did really like the robotic announcements when you first enter an area.

Anyway, good job, honestly, all these mistakes are something easily fixable and you certainly made an interesting game jam game. I'm looking forward to whatever you decide to make next. :)