One of multiple new features found in Serious Sam 4 is a skill tree, that enables you to unlock various new abilities and perks.
Of course, to unlock abilities on the tree you need skill points, and you don’t get them how you’d probably expect to in Serious Sam 4. That’s right, killing monsters won’t bag you any skill points. Instead, you need a keen eye for crates.
You gain your first skill point early on into Serious Sam 4. You’ll come across a rather inconspicuous looking brown crate, and upon opening it you’ll find a purple orb inside. When lifting it up it will disperse some kind of powder, and Sam will find that he now has a skill point to spend.
The rest of the skill points you’ll need to find yourself. Luckily for you, the crates are generally easy to spot thanks to them having a blue outline when you’re near them, however. If you want to find them all, make sure you undertake all optional missions found within levels, and explore!
Once you have some skill points, open up the menu and navigate to the S.A.M. tab to spend them. You can purchase a whole host of helpful abilities, including being able to dual-wield, ride monsters, and more. If you fail to find any skill points while playing, you can simply load up a chapter you’ve previously beaten to gain access to all the skill points available up to that point in the game. You’ll find yourself stripped of all your weapons and gadgets though.