Difficulty ramps up fast; should probably have the Bullet Hell or Runner tags. Neat that Saws will combine at high enough levels and fire faster. Even for a Jam game the story feels light, but this is mitigated with cute characters and vehicle designs that hint at a larger world (put another way, this is masterful minimalistic storytelling). Hard but enjoyable.
Post-jam suggestions: shield option (bullet-cutting melee or physical shield), convoy members with leveling, difficulty mitigation, save option if the story's extended, branching tuna tank options (non-attack), outrun booster (resets remaining enemies for the screen while they "catch up"), flying enemy/ally miniboss (gyrocoptor?) that seeks to attack but shoots slow, 90 degree perspective change as a win screen, +1 crate with each restart after X fight screens. Story expansion: "Purriosa's Portage" vs rival gangs/shipment companies; "delivery" and "deliverance" have the same word origin; tuna repopulation; Katamari Damacy-like size scaling.