Blasters and magic wands aren't as different as you might think.
There's a tendency to think that fantasy and science-fiction have almost nothing in common. It's not hard to see why: It would have been rather weird if Harry Potter had pulled a blaster on Voldemort, and Mass Effect would have been a very bizarre game if Saren had been a sorcerer rather than a rogue Spectre. But if you strip away the trappings, it can often been difficult to tell fantasy and sci-fi apart. In Issue 300 of The Escapist, Francis Cressotti says that it doesn't matter whether you're talking about arcane magic or pseudo-scientific technology, you're really talking about power.
For years, developers segregated magic and technology into realms that were palpably different from one another aesthetically and, to a degree, in terms of their respective attempts at justification. "Magic" in games was unknowable by its nature while "technology" liked to cite vague theories to satisfy the engineers.
But there are places where the boundaries break down. Technology, especially on the far out edge of physics, is becoming increasingly indistinguishable from magic, just as Arthur C. Clarke stated. By the same token, magic systems are - or can be - vastly complex and systematized. It's not always "you can shoot lightning from your hands because you're a freaking wizard;" in some cases, there are elaborate cosmologies and detailed metaphysics that explain magic very carefully according to unique but rigorous logic. Just as Clarke's axiom makes itself manifest in some science fiction games, Niven's converse dictum can define the magic of fantasy games.
Whether it's the near-future dystopia that is Deus Ex, or the high-fantasy of Baldur's Gate, the player is still exhibiting powers beyond those of regular folk. How it all works is just window dressing. You can read more about it in Cressotti's article, "A Kind of Magic."