I don't need 99% of its features, and I'm also a grumpy old man locked in my ways. Others have used ShareX on windows and love it. Licecap isn't as fully featured as gifcam, but it runs on windows and osx, and importantly for me, Linux via Wine. You don't get pure green output, gifcam stays happy. A lazy trick i found is to colour correct the display and turn the brightness down a little. It uses pure green internally to key the transparent bits (thus keeping size down), but if you record pure green, like the y-axis handle in houdini, it acts like a flood fill, ruining the resultant gif. One quirk with it though, be careful with bright green. My new favourite gif tool for windows (thanks Farmfield for the headsup):
There's a new contender for the gif making throne! On windows at least ScreenToGif has the good clean capture UI of Licecap, better edit tools that Gifcam, and can write out to mp4 via ffmpeg as well as gif.