Flinthook

Some spoilers. Platinum isn't too difficult, but has a lot of boring farming. The main thing is don't give up. At first I barely killed the first boss, and then I couldn’t get to the second for a long time. Then he couldn't kill him. But after 20 hours of training and leveling up, I was already able to complete the last location, where I need to kill all three bosses + two phases of the main boss, and 2 times more levels than in the previous location. So practice, practice, practice and you can do it. Don't be afraid of time trials, they are very soft. Don't be afraid of running for points either, there is a trick with endless farming of combo points on fish with spikes, although 1000 combos will almost always be enough. And in hard mode, only the locations become more difficult, and even then it’s not critical, but the bosses remain as they were. Secret bosses are easier than ordinary bosses.
And basic tips: on the 1st boss ship on the left there is a secret location where you can get an item for good luck by following the fat pirate’s prompt. Do not spend coins on amulets for 100 and 250 coins, because they give almost nothing, and there are always not enough coins, with these 100 coins you can open up 100 more HP than you initially had, or all difficult modes on all bosses except the main one. DO NOT buy additional equipment other than the Immortality Diver Suit. It is so cheatingly strong on bosses and in difficult rooms that you need to do everything so that it drops more often. Try to buy slots for perks, increasing experience and HP first (except for the 2 most expensive ones). And before preparing for a mission, there is nothing better than perks for a triple shot, because it is much easier to hit, and the damage of each of 3 shots is 5 units, despite the fact that a single shot has 10. Next is the perk for bounce, because bouncing shots fly almost 2 times further, and the radius here is nowhere more critical and they also jump chaotically helping to get in. A damage perk for gold is required. Every 500 gold increases the damage of the shot by 1 for a single shot and by 2 for each projectile in a triple shot. The gain limit is for 2500 gold, as a result we get 15 damage for each of 3 projectiles with a triple shot, and only 15 for one projectile with a regular one, which is also more difficult to hit with a single shot, the choice is obvious. This kind of damage tears apart ordinary enemies in a second, and bosses without indestructible phases can be killed at close range before the immortality effect from the diving suit wears off. It is also desirable to have at least one perk for 3 points per radius, because the radius is severely lacking, especially on bosses. It is also desirable to have at least 1 perk for more gold, this is important. And the final mandatory perk is a couple of seconds of immortality after receiving damage. At a cost of 1 point, it will save you more than one playthrough, because very often when you fall into traps and are surrounded by many enemies, you will not be able to avoid a cloud of damage in a short time, and this perk is simply invaluable. If possible, take 2 perks for relics, so as not to spend hours farming them after all the trophies. And then it depends on the situation, for example, running during timed races, if you don’t have time, etc.