Minor update for 2021:
Level 3 has been converted to UDMF from Boom (Doom II format), which allows me to add some dialogue; this conversion required me to re-script the doors, but other than that the process went quite smoothly in GZDoom Builder! The main purpose of this dialogue is to test out npc conversations for level 4, which will feature a few!
Your ally ninja(s) at the beginning of level 3 will trade you some for 10 ninja stars. I've also updated the "help" screen to reference how to initiate a conversation! Download the latest version to try it out for yourself!!