If the instrument at your disposal is monophonic (can only play one note at a time), you cannot play chords the way they were meant to be played, so you need to play arpeggios instead.
Sounds familiar? Indeed, the (real) KORG MS-10 is a monophonic synthesizer. On the other hand, the Nintendo version (KORG DS-10) has two voices (SYNTH1 and SYNTH2) and four drum tracks so we could probably use three drum channels to play chords, I guess. It seems however to be quite painful and it kinda defeats the purpose of having drums.
If the the first oscillator, VCO1 plays the first note of chord, the second oscillator, VCO2 could be used to get the second note of the chord, by shifting the pitch of the first oscillator. If you don't mind devoting two synths for playing chords, then you could possibly play triads and quads that way.
Anyways, it seems that if we really want to play chords on the DS-10 without getting too complicated and tying up too many synths, we probably will have to "arpeggiate" them.
In the video above, we make use of arpeggios to simulate chords. The first voice (SYNTH1) has the first four pitches of the C major scale (C, D, E, F) played as quarter notes. The second voice (SYNTH2) accompanies the first voice with the corresponding first four diatonic chords (C, Dm, Em, F).