*sigh* I'll have something more substantial up in the coming week. But for now, a terminology note. I propose that "hybrid" and "chimera" not be strictly interchangeable.
With regard to furries, a hybrid should be an individual body (exact definition subject to twinning and conjoinment) with approximately blended features of two or more species, allowing for variegated expression of those species' individual features. A chimera is more of a Mr.-Potato-Head approach, with swaths of body being one species or another (or one genotype or another, but this is harder to make out). Multiple heads being distinct species is popular and supported by mythology.
With regard to puzzles, a single-grid puzzle would be a hybrid if the constituent genres' rules were used in tandem to arrive at a single solution. A chimera calls on each set of rules separately to arrive at independent solutions.
ETA: The puzzle Grant is talking about is here. And yes, that's where I got "chimera" from.