are the RPG systems that of D&D

[Jackal]

because the last few kickstarted games tried using their own systems and they were awful

[tomimt]

This uses Numenera rule set. Though the original Planescape:Torment was very liberal with D&D rules in the first place.

[Void]

Generally speaking it is a Cypher System game, but specifically it is based on Monte Cook's Numenera tabletop RPG and its setting, with their own tweaks such as their action economy being different to accomodate their crisis system.

[Morgian]

In short: no, this is not D&D or even similar.

(I wish there were more computer games using the 3.5 system, but besides NWN 2 (MotB was great) and Temple of Elemental Evil nothing came out.)

[Jotun]

Icewind Dale 2 was kinda based on 3.5 if I remember correctly.