In Street Fighter 4, to unlock all of the characters, you had to play through arcade mode with each and every one. Even set on one round on the easiest setting, this took like 6 hours. For reasons I've suppressed from my memory, I had to do this three times - and it's fucking boring as hell, let me tell you. The AI is completely broken, so there's no reason one should ever want to play offline. Luckily, Super Street Fighter 4 had every character unlocked from the start, thank the heavens for that.
Also, once I misplaced my memory card for my PS2. Because I was bored, I decided to replay Half-life from start to finish in one sitting. The game froze just as I got to Xen, the first and only time my PS2 ever failed me.