Honestly, Contra might be one of the most well-tuned and tightest games on the NES outside of like, Super Mario Bros. Fantastic level design and super solid controls really make this one of the all-timers on the console.

But I think what stands out is the difficulty, which hits a real sweet spot of being tough but still pretty doable. It can be a bit maddening at points, and the game isn't always ENTIRELY fair (fuck that one turret guy near the start of Stage 7. Pure cheap shot) but every time you play, you make that little bit more progress, and when the game only takes half an hour to beat, well, it becomes real easy to want to see it through.

There's a reason why AVGN always used this as his go-to "good video game"

For all the trial-and-error gameplay and hilariously mean and petty traps, I think what makes IWBTG hold up surprisingly well a decade and a half later is that there is a genuinely really enjoyable click and feel to the platforming. Something really fun about being basically a flea trying to navigate a universe that wants you absolutely dead at absolutely every turn. Plus, weirdly satisfying jump sound, honestly.

Of course, there's quite a lot about this game that screams "amateur freeware game from 2007", from being extremely buggy and unstable (though the fan remaster fixed that at least) to having quite a few really shitty parts that stick out like a sore thumb even for a game designed to be as obnoxious as possible. That Bowser boss fight in particular is a real crowning example of "this isn't even hard, it's just really tedious".

Regardless...it's a classic, in its own, weird little way. There's a reason every YouTuber in the 2000's did a rage-through of it and why it's proved to be a pretty influential game in the long run. For better or worse.