a) Start Shadow Tactics.
b) See the purple screen.
c) Close the game via ALT+F4 or Taskmanager.
d) Go to Steam Folder\steamapps\common\Shadow Tactics\Shadow Tactics_Data
e) Upload your output_log.txt here or send it to email@example.com
NOTE: The output_log.txt is overwritten every time you start the game, so it only helps us if you send the version that was created right after the purple screen appeared and you closed the game.