There is a delicate line with pizza these days — as thin as the finest Neapolitan crust — that separates mere love from absolute obsession.

Tom Grim knew he'd begun to spiral into the pizza-geek abyss when he nearly burned down his house by rigging the self-clean function of his brick-lined oven to reach optimal pizza-making temperatures of 800-plus degrees. But that didn't give him pause. Instead, he installed a $10,000 wood-fired pizza hearth in his home kitchen. Then he put one onto the back of a refurbished 1949 REO Speedwagon that his business partner, Stalin Bedon, bought on eBay ("after more than a few beers"), so they could drive their pizza passion anywhere. First came Hopewell, and their first actual restaurant, a picturesque carriage house with stained-glass windows and a breezy patio that is a paradise for puffy-crusted rounds topped with sweet clouds of buffalo mozzarella and the freshest local ingredients.

And now comes Philly, their latest destination, which just so happens to be a city in the throes of its own recent pizza obsession. What began with Osteria and Stella, then picked up speed with Zavino and Barbuzzo, is now rolling through streets on the back of Pitruco's pizza truck, gracing the Schuylkill's banks at In Riva (in East Falls), even lending the Andorra strip mall a taste of Campania class at respectable Pizzeria DiMeo, where even the water for the dough comes from Italy.

But the more we are exposed to the deceptively simple art of these Neapolitan-style pies — those smaller, soft-crusted rounds with minimalist toppings that cook for just moments in ovens at thermonuclear heats — the more it's clear they are not the same.

And, as far as I'm concerned, they are all chasing Nomad Pizza, whose most elemental pizzas, the Margherita and Marinara, are as close to perfection as I've tasted this side of Napoli. It begins with the dough, which is left to ferment for several days before cooking, and develops a complex malty sweetness. In the oven, it takes on an elegant constellation of char-spots, and an irresistibly savory, luxurious chew that dusts my lips with flour when my teeth sink deep into its crackly crust. It has a profoundly roasted flavor that lingers for hours after the meal is over. But Nomad's toppings are not to be overlooked, either, including an uncooked sauce that's not too sweet, too tart, or too salty, but a sunbeam of vivid tomato that brightens all the other ingredients — the milky sweetness of buffalo mozzarella with the Margherita, the dusky herbaceousness of oregano, whole basil leaves and zesty garlic with the Marinara, or the piquance of salami kissed with a golden drizzle of local honey on the Spicy Sopressata.

With such stellar basics, it's no wonder Grim and Bedon have chosen to keep their restaurant concept as pared down as possible — just great pizzas and salads, craft beers, and wine.

"The smaller the menu, the better," says Grim, who made his name in ice cream with successful Thomas Sweets in Princeton, and sees parallels between the two industries, with American pizza now finally going artisan two decades after he, Ben & Jerry's, and many others made their gourmet push in freezer sections of the 1980s.

He and Bedon have done a fine job of transforming the former Horizons, at Seventh and Kater, into something that reflects that minimalist casual spirit. The bilevel building looks very like a clubhouse, with corner cafe windows swung wide to the ground-floor open kitchen, where a copper-clad oven dome glows hot beside a rustic community table, and a rambling upstairs room with a bar and another community table that also hosts vintage movies weekly. With just a few crunchy salads to set the stage — a split-romaine heart drizzled with straight-ahead Caesar dressing and good anchovy stripes, or mixed greens topped with candied nuts and blue cheese — appetites are piqued but not distracted for the main event.

A few quibbles, though. If only they'd pull back the black curtains to let in some sunlight when it's not movie night that upstairs room would feel less like an attic rec room. The young service staff also lacked the kind of warmth I'd expect from a place that is all about obsessive passion, often seeming absent and distracted. The modest drink list — a new challenge, since the Hopewell Nomad is BYOB — is in the right vein, but a bit unfocused. The craft beers pay far less attention to local producers than the pizzas do, and lean toward heavier, less pizza-friendly styles (high-octane tripels, quads and strong ales, hoppy IPAs). The Italian wine list has good vino but largely ignores the pizza's native land of Campania, and, with few exceptions, the entire south.

There were also a couple of pizzas I didn't love. A seasonal white pie crisscrossed with whole asparagus stalks was awkward to eat. The quicker-fermenting "Roman-style" dough, Nomad's answer to Americans' taste for a thinner and crisper slice, had soaked in too much of a burnt flavor, and seemed, well, flat and one-dimensional next to the buoyant Neapolitan.

Leave the crunchy pies to the likes of Tacconelli's and SliCE. Nomad's glory is a quick-from-the-hearth pillow-edged affair, whose delicacy was never intended to stick out ramrod-straight into the air once cut. That's why these pies come whole with a DIY pizza slicer on the side, to prevent premature sogging.

And while I agree with Grim that the simplest pies are best, I've also had some wonderful pizzas with more elaborate ingredients (Bedon's pursuit). The arugula pie, topped with peppery tufts of Blue Moon Acres greens, is even better draped with the pink silk of prosciutto. Good porky crumbles from South Philly's Renaissance Sausage had the ideal texture and fennel pop alongside the molten splotches of mozzarella. The four-cheese "quattro formaggi" pizza (so often gloppy elsewhere) was subtly dynamic, with springy caciocavallo, Cherry Grove's earthy toma, creamy mozz, and Parmesan each lending distinct notes, all laced together with caramelized onions. I also loved Nomad's clam pie, the minced topping tender and full of flavor without getting soupy, piqued by an assertive tingle of chile and sunny oregano. And I cannot wait until late summer, when Nomad re-creates the sweet corn-and-truffled special from Hopewell I still dream about.

With such bold flavors ringing in my mouth, I'd go for a Nutella-smeared dessert pizza...if only I weren't already full of pizza. A more sensible solution is the airy espresso-soaked tiramisu. But for something special, do not miss the frozen delights from the Bent Spoon in Princeton, Grim's old scoop-shop stomping grounds. Two bites of sublimely creamy crème fraiche ice cream, followed by several spoonfuls of the crimson berry velvet known as Black and Blue, and I knew: A city whose love of both artisanal pizza and ice cream has clearly stepped deep into the obsession phase now has two more idols to worship.