For electronic sounds, there are many, many free options out there that are fantastic sounding. These are synths that I use in a lot of my own music:
All the GTG synths
I've used all of these in several tracks of mine, and some of then like Synth1, Tal-u-no and SQ8L are present in the great majority of my songs. They're all just a google search away.
Regarding Effects, here's a comprehensive list of great effects that you can use and again, some of them I use in many of my tracks, like the great reverb effect Ambience, great eq effects like SonEQ and SlickEQ:
I also recommend getting EVERYTHING from Variety Of Sound. FerricTDS is a staple of every single one of my mixes.
EDIT: Forgot the TDR Nova: http://www.tokyodawn.net/tdr-nova/
This is a MUST for any producer in a budget to help you mix and master your tracks. There are very few multiband eq/dynamics vsts out there that are this good, even ones you actually have to pay for. Must have.
I'll co-sign with Gario that the production was fine for the piece (vis-a-vis the standards).
Hate to sound like I'm nitpicking a small detail, but, while I didn't mind the guitar panning, I agreed with the others that the guitar and chiptune merely doubling the same lines for the entire track was disappointing as far wanting to hear more development and variation of ideas in an otherwise-cool concept piece. Could have used warp pipe jingle at 1:15 to transition to the Underground BGM; what's here right now is just an abrupt cut.
Total agreement there. There's nothing really there for that section except a slightly faster retread of the 1-1 theme; I get how it's holding just a simple tempo increase like the original song does, but for the arrangement standards here, we're looking for something a little more substantive, so consider what else you could do there so that final section stands more apart creatively from the first one.
Great potential here, Mike. The standards here push for a little more variation within such a short arrangement at only 2:31-long, but this is definitely creative and well in the right direction. If you're willing to revisit this one, we'd love to post it in some form, it would just need some sort of continuity or legit transition point between the Overworld and Underworld themes, and some more variation in your treatment of the Overworld theme. If you'd rather leave this piece as is, that's no problem, but I hope you'd be willing to submit more works of yours down the line. Cool stuff so far, but develop the writing/arrangement a bit further!