There are multiple layers at addressing the "lack of depth" of the plot and the MC being a sort of Mary-Chad-Sue.
If you want to implement struggle and challenges then the players have to *feel* some sort of genuine struggle and challenge.
That is, if you want to feel it "real" you have to stand a chance to fail and live the consequences.
Some games implement some form of combat. It's usually simplistic (we are in porn VN games after all!) but you can lose.
Other games transform struggle into "grind-fest" or some annoying mini-game (see Being a DIK).
However, do people who appreciated DS until now want this? Assuming the Dev is available to implement it (which is not free to him), that is.
And what would be the *concequences* of losing? Because there's no struggle if there's no challenge AND the challenge could fail.
Some games put in a quick "Game Over" (DS does it in one instance too). But it's not really "content" nor a plus. You just lose the game, you don't get a "feeling" of having lived a valuable experience from a trivial Game Over.
Other games shut down relationship pathways or "kill" the character that was the subject of that specific struggle having gone bad.
Once again: in real life, you take the hit and move on. Because there's no "turning back", we get a one-way ticket in life.
But in a game? No. We just failed challenge XYZ and lost our dear NNNN girl. Consequence: load from last save and move on.
In order to have meaningful challenges a simple porn game should switch to hard-core "survival sandbox", like Eve Online, where you cannot "reload". You pay harsh consequences but you have invested so many years to progress to your current status, that you don't think one second to throw away years of efforts just to recover 1 pixellated girl.
Last but not least: this is one of the more and more rare games where the MC is not a "boy". In SC, the MC not an idiot. Is not fumbling his way through life. Is not wanted by all women just because he has born with a Zeppelin-size penis (plenty of VNs doing this).
In this game, the MC is a though MFer who takes what he wants with brain or force or personality and is not ashamed of it.
Now, all you can do to keep this kind of personality and "success persona" is to introduce some irrelevant / cosmetic challenges. But they are irrelevant and won't have any suspension of disbelief, so why put them in in the first place?
In the end this is a one-of-a-kind PORN game. No Tolstoy or Margaret Mitchell "saga" or plot. Just a though guy with a fairly big sword and a fairly big dick taking what he can from an hostile world.
Heck: compare SC's plot with any porn movie... the plot is still tons better than all of them!
