Field guide
01Upgrade the current blocker
The official store description frames progression around earning money, improving gear, completing quests and reaching new islands. That makes the active objective the best first filter for spending. If a boss has not spawned, a stronger weapon may not solve the missing quest step; if the route is unlocked but distant, a travel upgrade may matter more.
This page uses purchase priority rather than a permanent tier list because the available research does not establish every price or effect. The goal is to reduce waste by connecting one purchase to one visible obstacle. It is not a promise that the same order is optimal in every co-op group or future patch.
02Keep bullet upgrades separate from attachments
Current weapon research distinguishes bullet upgrades from attachment slots. Bullet upgrades are described as a damage-progression path, while attachments are separate equipment choices. Treat those as two questions: can the current weapon handle the target, and does an attachment choice support the way you use it?
The Steam achievement list includes both a general upgrade goal and a fully equipped goal, but achievement names alone do not reveal every compatibility rule. Do not infer that four items work on every gun or that one attachment combination is required. Check the live inventory interface before relying on a specific compatibility claim.
03Make a weapon upgrade before a boss attempt
The Giant Piranha route is a clear example of a combat-first spend: a player needs sustained pressure on the boss while managing nearby threats. A shotgun and its bullet upgrades fit that role, but their exact cost is not a stable rule for every build. The transferable principle is to finish the damage plan before spending the boss bait.
Once the current weapon can perform its job reliably, stop shopping long enough to test the fight. Endless preparation cannot replace learning the route, movement and hand-in sequence. If an attempt fails, change the part that actually failed instead of buying unrelated upgrades by default.
04Use utility purchases for utility problems
The Radar works as a navigation aid and Dynamite as an early collection utility. Those purchases answer different questions from a gun upgrade: where to travel and how to gather fish. A player who is lost or cannot stock supplies may benefit more from utility than from another damage purchase.
Early-build prices are not preserved as an authoritative table. Recheck the shop on the current build before budgeting around a number. The durable advice is to match navigation tools to travel needs and collection tools to collection needs.
05Delay full catalogues until they can be verified
An upgrade guide becomes misleading when it presents guessed costs, invented stat gains or invisible prerequisites as fact. Weapon bullets, attachments, boat engines and utility tools exist, but a complete official upgrade database is not available. This page names that gap instead of hiding it behind a long table.
Use Weapons when selecting a combat role and Boat Upgrades when the question is travel. Add a future row only after its name, current cost, effect and game version can be checked. That process gives the wiki a revision trail and keeps an update from silently rewriting an old recommendation.