When rob says it’s brilliant - I guessing he means it brilliant for this dramatic medium - acting lessons is a great VN - but that’s it .. as you say it’s no Angel heart or usual suspects - it isn’t competing with them it’s competitors are ‘big brother’ etc
Okay, the medium thing has come up enough times over the past to be worth addressing properly (if a point keeps coming up, it's obviously not off-topic). Yes, it is a VN and like for like comparisons should be against other VNs. But when looking at specific elements, it's also great to compare those elements to matching things. In other words, if we are looking at render quality, it is just as fair to compare it to art renders not produced for a game as those that are. When looking at a plot or storytelling, it is fair to compare to any other plot or storytelling. I quote movies often because they too are visual storytelling, and they are one of Doc's own sources of inspiration.
However, just within the VN medium, this game has many comparisons, and several of them have been made more than once. Repeatedly people have mentioned
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which is another VN that covers dark plotlines and kills a significant love-interest character - only better. If you haven't played that one yet, do give it a go.
If you want to compare good characterizations then I'd suggest taking a look at "Our Fate" (link in my sig), which also has it's share of dark elements, and even someone with cancer, but honestly, once again, better, though not as 'pretty'.
If you want to see what looks to be a truly massive and ambitious plot done with good pacing, give "Retrieving the Past" a look (again link in my sig) though that one is a long, long way from complete and doesn't have the great characterisation and dialogue, at least yet - though the render quality is 100 times better than Acting Lessons, and it has many of the same characters due to collaboration between the devs. It's worth it just for the satisfaction of getting to punch Dick in the face when he treats Rena badly.
There are many elements to a game. Great writing of dialogue and characters doesn't mean that the plot itself will be good, or the renders will be, etc. Some games are brilliantly written and just not actually fun to play.
You brought up Big Brother, mostly to mock it's 'plot' and writing I think, but actually, think about this. So long after the game was completely abandoned by the dev, it still has a thriving community of supporters and fans expanding it - because it did one thing absolutely brilliantly - it allowed people to mod and expand it. That's why Minecraft and similar games did so well even though, to be totally honest, the graphics were absolutely awful, and the game itself certainly wasn't plot-fuelled like other games it competed against from C&C to GTA.