Strangely enough the seed was mislabeled, and the "ZS" plant turned out to be Zolotye Kupola - one of the original parents in the Yellow Project. It was nice to revisit them and I was pleasantly surprised that ZK turned out to be one of the most resistant to the hot humid summer blights we had, although the fruit cracked pretty badly outdoors.

Our 2022 season flipped from typically cold to unprecedented, relentless heat and humidity from June onwards. I managed to get a decent fruit set by running fans every day in the greenhouse. All the extra plants got moved outdoors in the second week of June - never ever this early before - and I had ripe fruit outdoors in July - again, this has never happened. So for us it really was an unprecedented warm season.

I had a problem with my camera and missed getting pics of everything but I do have a few, will find and post some.

The bicolor F2 were fun. I kept some indeterminates in a tight row and got at least a few fruit of each of those - they were the only bicolors, one green and one 'yellow'. More surprising, there were several pinks. I had forgotten that a pink gene was floating around in the non bicolor parent, there it is. I ended up with four determinates, which is good for 11 plants. One pink and three reds.
Plants with the large early buds produced some nice large ruffly fruits. A determinate red one and the indeterminate bicolor earned the nickname of 'rumpus' for the riot of ruffles and a tendency to lob fruit at me if I didn't pick them when ready. Both really productive plants, but I was most impressed with the bicolor rumpus, for being super productive and also having great foliage and stem health. So I think I will have to grow this one out and hope to find determinates in the F3.

Yellow Project - it was interesting to see how far the two F5 sibling lines diverged for fruit size. Taste is starting to converge though, on the combination of sweet, fruity and tangy. At least they got good reviews in spite of the variation, so will grow again by popular demand.

Both YP lines were the most susceptible of all to the early heat and dropped so many blossoms that most of them were moved outdoors asap. The most heat tolerant of each line was kept inside. In spite of being in quite a small pot, the best Fruity Finch was loaded with small fruit and was the most heat, disease and stress resistant of the YP overall. The best tasting Lemon Squeeze was one of the outdoors, with large and excellent fruit, but highly susceptible to the leaf scourge of hot and humid weather. I will have to grow some of both again next year.

Great looking tomatoes!

Love especially the Red Det Rumpus and those yellows with green hue. I am sure you will find a bicolour out of those dets if you choose to continue them.

2022 sure was a difficult season, very high temps also in the Northen Europe, lots of dropping flowers and miserable looking leaves. Good trick to use a fan to get better pollination, wouldn’t thought of that myself.

Have you figured out the inheritance of the ruffled fruit form? Is it a single recessive gene or more? I love those almost cherry size mini-beef tomatoes, should try to create one myself.

@Pippin Yes, I can hardly complain about the temperatures we endured, when Europe and others suffered so much more severely. It was really notable that so many places had the same problems in one degree or another, for a very dry and hot season. The humidity here was quite bad as well, and it sounds like you had similar conditions, which are really tough on the tomato leaves. We normally have the humid heat for no more than a week or two, so I haven't had the opportunity to select for resistance.

The ruffled trait: hmmm I think it must be recessive and complex, further complicated by environmental interactions.
I believe it is recessive because the Skipper minibeef which was the determinate parent in this cross was unusual in showing the ruffle tendency, those nicely rounded locules turning up even though the fruit had only the locule number gene and not fas. It is not a common trait in that line, so must have been the result of several recessive genes combining along the way. The bicolor parent is ruffled, so that explains the amount of ruffling in the F2, as it was coming from both parents.

The tendency for single locules to go rogue out of the main structure seems to be triggered by environmental conditions and a plant survival strategy, where the locule in question managed to pollinate while others were not, and the plant goes ahead and grows it independently ahead of the others. (Both of the 'Rumpus' plants had plenty of nicely shaped fruit which set in the more optimal conditions.) Thus you get strange shapes and uneven ripening, which makes ruffles a poor shape for challenging environments, at least from the eater's standpoint. But they are awfully cute.

Other genes, for pointed, longer or heart shaped fruit can help to stabilize fas shapes and ruffles. I think the most regular-fruited ruffled plant I've grown was KarenO's pink heirloom (now I've forgotten the name) really large, deep and rounded and perfectly ruffled. OTOH the most prone to catfacing and irregular shapes in ruffles are the flattest ones, like PI120256. So my advice would be to choose a ruffly heart or similar, to cross with a cherry. The fas gene will add something to size but it shouldn't be too hard to select for smaller fruit closer to cherry size.

I wonder about fas and the number of locules it produces. There seems to be variation in that, and many of the ruffled fruits seem to have an overstock of locules, just too many to accomodate in their shape. So perhaps that is something to tweak as well, to get just the right number of locules that will lay flat and perfect around the size of the fruit.

Skipper Pink, my all time favorite and very very close to stable or MUST be, actually wasn't stable for shape details this summer. I had a choice between the somewhat reduced point shown on the left (which is typical of most) and the more pronounced point which happened to also be on the earliest plant and most consistent all around - at least it's one of two that I kept in the greenhouse and it had the expected growth habit, disease resistance and production. Taste has been very consistent with these for generations, and they are lovely. Now at F9. So I saved seed from the pointier fruit and we'll see how stable that is next year.
The seedlings this season were a motley crew - one was a tricot, one afaict a monocot! so I wondered about growth habit stability. But at the potting up and flowering stage I checked all the plants and they were entirely consistent in growth habit pattern. So that part is stable enough.
This is a GF fruit but it ripens to a dark pink. Only the green gel and flower color are there to confirm gf.