A spin-off is not always a good idea. Just because a franchise is successful in one genre doesn't mean that its concepts will transfer over to another – but Devil Survivor pulls it off. The hallmarks of the Shin Megami Tensei role-playing games, like demon fusion and a macabre story, make a smooth transition into the world of grid-based encounters and ­strategic combat.

Devil Survivor works well because it plays to the series' strengths. Rather than present another ''go here, hit this'' tactics experience, the game uses slices of traditional turn-based battles to resolve clashes on the field. Each of your units is an entire party – comprised of one hero character and two demons – and each attack is a round of combat in which you can cast spells and use special abilities. Victory ultimately rests in your ability to exploit enemy weaknesses to gain the upper hand, which means the demons you assign to each character is a crucial part of your strategy.

Preparing your teams for battle is far more than administrative busywork; the time I spent obtaining new skills and fusing demons was almost equal to the time I spent in combat. These addictive sub-systems feed into the gameplay perfectly, so even when I was grinding to beat a tough fight (which happened often), I was still having a good time. Even the story is compelling; the tale of the heroes' efforts to prevent an impending catastrophe in Tokyo never feels like a cheap excuse to ferry you from one fight to the next.

While combat is usually entertaining, it suffers from one major problem: Chance plays an inordinately large role. The enemies don't attack with any degree of intelligence, so they just whap your party members randomly. Sometimes this works in your favor, but it also means that you can get blindsided if one of your units takes an unlucky hit. Thankfully, the ability to freely engage in skirmish battles means that you can eventually just steamroll through trouble spots after gaining a few levels.

Developing and executing strategies would feel more significant if the enemies' behavior was consistent, but Devil Survivor still comes together as a clever blend of tactics and RPG conventions. Even if you've never played a Shin Megami Tensei title before, the darkly intriguing premise and unique gameplay make this an excellent place to start.