Hexagram is a live effect that replays samples and grains from the past to create an ambient texture from an input source. It's different to Granular in that it samples live audio and can only be used with headphones or a suitable live input and output using TRRS. It augments the incoming signal rather than acting as a standalone instrument like Granular. Hexagram is also less granular than... Granular; all effects are global, it's a smaller simpler program with just one screen.
The Playdate doesn't support pass-through audio. If using Hexagram in a music setup the source signal should be split and joined again in a mixer, you'll need a TRRS adapter.
+------------+ +-----------+
+----------------+ | | | | /
| | ----| PLAYDATE |--------| MIXER | /
| SOURCE/SYNTH ------/ | | | |---- | OUT
| | \ +------------+ | | \
+----------------+ \ | | \
\_________________________| |
+-----------+