It's been a while since iCE 3 was released in 2016. It was the outcome of several years of developing, testing and tuning. It played at a reasonable strength and had almost all features a chess engine should have. It missed only one feature that was asked about a lot, the ability to use more than 1 core for the calculation.
Sometimes it seemed that people cared more about this feature than actual strength. iCE was never allowed to play into the Top Chess Engine Championship (TCEC) although it was stronger than most of the participating engines. Maybe to save some 32 core engines from embarressment being beaten by a single core one (not that I actually care about that).
As an engine author I was not really interested in this feature as it is just means the engine calculates faster instead of smarter. But as all the other engines supported it, it felt more and more like a missing feature. So I decided that iCE 4 will support multi processor calculation, although this required a rewite of some vital parts of the engine.
The new engine version is available at my website
As large parts have been rewritten it might contain still one or more bugs I was not able to detect in my tests. So use at your own risk 😏