with little extras, such as new items, Steam achievements or even a new difficulty mode, more challenging than the Tactician mode.
All those would be nice, especially harder difficulty mode that I heard many requests for. Not sure why we would need Game+ for it.
I can’t quite imagine what you want from game plus, in spite of game somehow giving you special rewards for replaying it - I would hope that the alleged “no two playthroughs are the same” would already provide enough of an incentive.
That said, I am not a New Game+ player. Never seen a point of it.