There’s not a lot else to say about a system that takes up twenty or so pages in a small-format book. Four skills, a universal resolution mechanic, and a simple method for the GM to create difficulty: there aren’t a lot of moving parts to go wrong. Other systems have lots of fiddly bits that are easy to exploit, hard to master, and can blow immersion at inopportune moments. InSpectres is purpose-built: work as a group to create wacky monster mystery; have fun.
However, the core concept around which the game is built is easily transferable to pretty much any other system: you can’t really get stuck in an investigation because the players are inventing the clues and giving them meaning. Most mystery games have a justified reputation of being really easy to screw up unless the GM is excellent and the players are in sync with his or her style. It all comes down to how it’s nigh impossible to make scenarios without a breadcrumb trail of clues (that may look suspiciously like a railroad if done really wrong), and missing enough of them (or getting them and not understanding them) is sufficient to completely, well, derail the adventure. It’s such a problem that the Gumshoe system (used in Esoterrorists and Trail of Cthulu) is designed around a method to ensure clues in mysteries can’t be missed by bad rolls.
InSpectres turns the problem on its head. While I have no actual data on the subject, my strong suspicion is that typical RPG mysteries are way more interesting to the GM than to the players. It’s very easy to go from “players feel clever for figuring this out” to “players are grudgingly collecting their plot coupons so they can get to the fight scene.” InSpectres invites full player investment through the simple expedient of giving them complete agency over the plot. There’s no worry that players are going to be bored by the clues they find, because they’re inventing them. Sure, they trend toward the wacky, but it’s wacky fun, and that’s something that can be much more hit or miss in traditional investigative games. With a more serious setting, crunchy system, and play contract, you might even get rid of the wacky while keeping the fun.
InSpectres is a purpose-built game engine around an intriguing core concept. It works really well in and of itself, but the really cool thing about it is that it’s basically a low-impact testing method for an idea that could be easily ported to virtually any other game with minimal difficulty. Why don’t we just let the players define the clues? After a couple of sessions of InSpectres, you’ll have fewer objections to the idea than you might think.