As of three hours ago, I can say that I’ve completed the entire single-player portion of the Half-Life franchise. I played the original game in the series years ago, and last year, upon seeing that the entire Half-Life collection was on sale on Steam for ten bucks, I quickly made the purchase. I then replayed the original (in the full glory of its Source Engine remake), the second, and the episodes, before moving on to Lost Coast and the expansion packs for the original.

As I lifted my right hand from my mouse after the final scene of Blue Shift, two thoughts struck me: 1) “Wow, that was pretty awesome” and 2) “I didn’t die much, did I?” Now, I have a confession to make: I almost never play games on higher difficulty settings. Compared to hardcore gamers, I suck at first-person shooters. But even then, in most FPSs, there are always a few sections that I have to redo several times, which can range from mildly frustrating (e.g. Command and Conquer: Renegade) to rage-quit-worthy (e.g. Far Cry). I didn’t really experience this issue with the Half-Life games. Yet, I still felt as if all of them were challenging. If not repeated death, what made these games tough? We’ll take a look after the break.

The most obvious non-death-related challenge that stands out about the Half-Life games its use of environmental puzzles. Often, you’ll need to flip switches, complete circuits, or rearrange boxes in order to progress. There’s a pretty memorable puzzle in Blue Shift that involves lining up a bunch of barrels in a pool of toxic coolant in order to make a series of platforms that you can use to leap across. To give another example, the entirety of Episode Two’s “Freeman Pontifex” chapter is an elaborate puzzle centred around balancing a broken bridge so that a buggy can be driven over it. Sure, you’ll spend a lot of your time in the Half-Life games shooting monsters and blowing stuff up, but you’ll also spend a lot of time trying to solve some sort of puzzle in order to progress. Heck, half the time, blowing stuff up is the solution to the puzzle!

Environmental puzzles don’t pose the threat of imminent death (unless you utterly fail at first-person platforming, which I unfortunately do). But they do pose a more cerebral challenge, as opposed to pure shooting, which is mainly a test of your fine motor skills. (Let’s face it: the enemy AI in the Half-Life games isn’t all that smart.) Puzzles also play a role in varying the flow and pacing of the game. If all you’re doing is shooting zombies, even if it’s difficult, after doing it for a while, you’ll eventually stop feeling as if you’re being challenged. By breaking up the shooting sections with puzzle gameplay, each new round of blasting aliens to smithereens feels fresh.

The other thing that makes the Half-Life games seem difficult is harder to pin down, and it took me a while to put my finger on it, but I think it boils down to this: you always feel like you might be on the verge of death. Part of that is in the element of surprise; headcrabs and other monsters are liable to leap out of dark corners at any moment, keeping you on your toes. Half-Life 2 even introduced special speedy headcrabs that poisoned you, bringing you to within an inch of death before allowing your health to recover.

But the brilliance of the Half-Life lies not just in enemy design, but also in how those enemies are placed in the game along with health/energy power-ups. You will rarely have full health or energy at any point during a Half-Life game. In fact, you’ll usually only make do with a fraction of your potential health and energy. If you’ve just picked up a bunch of medpaks, chances are that a vicious enemy is just around the corner. This way, you always feel unsafe, like you’re facing a huge challenge, even though you rarely actually die.

Half-Life games present players with a different kind of difficulty than one might be used to. The games aren’t about fighting off wave after wave after wave of ever more powerful enemies. They work your brain, and they constantly threaten you with the possibility of death. However, they don’t actually need to kill you in order to make themselves difficult. Instead, they’re built with the knowledge that the fear of death is often enough to create a sense of challenge.