For reference, the following description is on both Steam and GOG (2 separate companies that are not Larian) which suggests that Larian approved of the description in these places where the game can be purchased:
Evolved turn-based combat, based on the D&D 5e ruleset. Team-based initiative, advantage & disadvantage, and roll modifiers join combat cameras, expanded environmental interactions, and a new fluidity in combat that rewards strategy and foresight.
For reference, the following is a snippet of the description for Solasta on GOG:
True to the Tabletop Wizards of the Coast granted Tactical Adventures a license to use the Dungeons and Dragons SRD 5.1 Ruleset, further anchoring our will to make the most faithful video game adaptation with the Tabletop Ruleset and craft the game you are hoping for!
Those snippets are just to save people some time.
Originally Posted by RagnarokCzD
Originally Posted by GM4Him
But, again, when the homebrew steers so much from the original rules that you are no longer playing a game even closely resembling the original rules, THAT is what I have an issue with.
But are you able to draw a line?
This is an interesting question. How much change is too much? When is it no longer "based on". And how do you define "based on" is important to understand as well. To me, based on means there will be little derivation; if any. That is only my interpretation.
As a customer I can say that I, personally, did not go looking for all the interviews. I read what was on GOG and paid for the game. I also am not familiar with D&D 5e so my point is only that some people just read the description presented at the store. I believe it can also be argued, however, that a person should do their due diligence and research before they buy. That would be fair to say, right?
