Had to put all those hours spent reading about 3D rotations into use somehow ;p

I am! Long time no chat :)

Thanks it's a pleasure to read!!!

First, I'd recommend finding some free to use soundfonts that won't get you into copyright trouble. While video game soundfonts are in grey area, they should be fine to use, as those samples do not belong to the companies that made those games anyway. If you're unsure, you can just use SGM soundfont, it's widely used by many composers and developers, including people like Toby Fox, which will allow you to achieve the videogame music vibe.
Second, some chiptune vst would be nice, There are many out there, but I'd recommend Soraboy and Magical 8bit plugin 2, but if you really want to achieve the closest possible NES-like sound without a tracker, then you might wanna get Nes VST.
Third, try to combine samples, vsts and soundfonts mentioned above, as the combo of sampled organic instruments with synths (chitpune-like ones) is a "shortcut" to video game music. Do not be afraid to manually compress, bitcrush and EQ cut some instruments for a more crunchy sound. Just in general try to experiment with low-quality samples, some of them have some sort of charm due to their crunchiness.
So yeah, in general, If you're using FL studio, then 3xOsc, Soundfont player (bundled with soundfonts like SGM and Airfont), Soraboy, Magical 8bit plugin should be enough for instruments, and when it comes to effects, you can use pretty much any plugins for compression, EQ, bitcrush and so on. I'll recommend avoid automated sidechain, if you need it, just do it manually through note velocity or volume automation clip, that way your track won't have too much of a "modern" or "professional" feel to it. Despite that, I'd recommend using OTT from time to time, since it's a really easy way to fix a sample with screwed eq, but don't use it too much.