Tall Grass

Every blade of tall grass hides something: a shard, a heart or a monster. Trample it and find out. Cleared tiles reveal how many monsters lurk in the eight tiles around them, so every step is a read as much as a gamble.
The gate opens before the field is cleared: leave with what you have or push deeper for the shards and upgrades you'll need when the Pumpking wakes. One thumb, one verb, fully turn-based, nothing happens until you move, so there are no reflexes to fail.