Hi again @andytheyoo
I like this track, it's appealing & you did a pretty good job with mixing as well as for the arrangement
You perhaps still have a tiny bit too much low end and at some points in the track you have peaking levels going into the red ( mainly because of the transient heavy lead /pluck synth playing in the intro & transition later in the track ) but really those are minor issues. A slight boost in the 2.5K / 3K frequency range could be nice too IMO, but doing this, pay attention & tame your ambient white noise which is already quite present.
I wasn't sure about this intro and this synth sound choice when first listening to the track, this synth sounds more like a kind of "future-bass" style synth comparing to the more chilled style of the all mix but listening several time to it, it actually creates a nice variation in the track.
I like the different synths layers and the way you're progressively bringing them into the track & blending them together, nice work, it keeps the track interesting even when listening to it several times.
So yes, nice one & great work
About Mono & Stereo Mixes :
Except if you're working with a 100 % Mono audio material source ( like a pure mono channel audio recording ) and on a true mono ( single output ) channel in a DAW, nothing is really mono inside your DAW because everything ends up to a stereo output and there's always 2 channels out per track.
What's happening inside DAWs when setting a track to Mono is that an equal audio signal is send to both speakers while in Stereo, two distinct audio signals are send to the respective Left & Right speakers ( we just considerate a standard 2 speakers monitoring/listening setup here ).
So because of the way our ears perceive sound, an equal audio signal sent to the Left & Right speaker will make our brain think that the sound is coming from the center point between those speakers, especially if we're standing in the middle.
In Stereo, 2 distinct audio signals are send respectively to the Left & the Right speaker. Theoretically if those signals are both the same it should sound exactly like in Mono, but again, because of the way our ears perceives sound and extremely short micro-delays + the way that sound travels from each speaker to our Left & Right ear, it will actually sound slightly different and less centered.
Now if those 2 distinct audio signals are different ( in pitch, delay & time, level or other effects ) it will result in a more wide/spacey perception of sound for our ears & brain, and that's where it's getting interesting actually.
When listening at a centered position between 2 speakers, the Mono mix will most of the time sound more present, loud and right in your face because of that centered sound perception from our brain, the sound travel seems shorter to us.
In Stereo and using even 2 slight different audio signals, our ears & brain will perceive the sound more wide and a bit further away giving us this perception of space, time and deepness of audio field.
So the relation between the two is really about contrast & audio placement in space. Though this is less obvious on headphones, a 100% Mono mix could sound a bit lifeless because the exact same signal will come from the center of the Left & Right headphone driver. On close back monitoring headphones the difference can be hard to catch because the drivers are isolated, but it should be more obvious with open back headphones because of the vents around the drivers leading to a listening experience closer to speakers. That said, the easiest & best way to compare a Mix in Mono & Stereo and the balance between both is on monitors & speakers.
If you mix 100% Mono, you're loosing that chance to create wide & full mixes and the ability to use effects like delays, pitch and reverb to their best to create space and deepness in your mix. Another problem can be that many instruments can fight/duel for the same frequency range, especially in the low end spectrum.
If you Mix 100% Stereo, chances are that you will run into phasing issues and a lack of clarity, presence and mixes loosing punch & sounding dull or "distant", you get the picture.
So yes, it's really a matter of creating contrast, because our ears & brain need something to sit in the center in order to "re-place" in time & space different sounds coming from Left or Right and creating that perception of a wider sound.
Back in the days, DJs had to make sure that their mixes where Mono compatible for clubs, because the PA audio systems they were playing back their mixes where mostly Mono, this is less & less true nowadays but still it's good to pay attention to Mono & Stereo and to keep a certain amount of Mono content in your mix, especially for important & low end elements like kick & bass.
In the case of your Mix, you did quite well and when switching to Mono listening, your mix is perfectly centered and a bit louder than when listening in stereo, something you can also compensate to taste when doing your final mixing/mastering on your 2 buss channel.
If you haven't done yet, I suggest you to watch this nice & very informative tutorial from Nate Raubenheimer aka Protoculture/Shadow Chronicles about creating wide Stereo Mixes here on S.A
And again, nice track & good work, keep it on