I really enjoy Iron Pineapple’s “Steam Dumpster Diving” series which covers a variety of obscure “souls-like” games from the indies to solo and student projects. The series naturally raises the question “What is a souls-like?” Generally, a souls-like is any game that is somehow evocative of Dark Souls and its successors. However, the practical consensus among the games in the series, is that a “souls-like” is a game with a dodge roll.
The dodge roll, as popularized by Dark Souls, has two distinct components: An initial moment of invulnerability (i-frames), and a quick repositioning of the character. This can be contrasted with older interpretations of rolling in games–for example in, Zelda: Ocarina of Time, the character can roll (or backflip or side-jump), but this does not have initial i-frames, and mainly serves to quickly reposition the character.
Repositioning and i-frames represent two different defensive modes. Repositioning tends to be the more intuitive mode; if an opponent swings a sword, you get out of the way. i-frames tend to be more counterintuitive, because i-frames allow you to roll directly through the sword. In fact, rolling into a sword is usually better than rolling away from it, because it reduces the amount of time you need to be invulnerable to pass through it.