If you enjoy this, you should check out https://www.dwitter.net (or beta.dwitter.net for the improved interface that lets you decompress compressed dweets) – the author is very active there, and it’s pretty fun to take a crack at. There’s also a cool remix feature so you can make your own version of other people’s dweets!
: Compressed dweets use multi-byte Unicode characters to encode stuff, along with an embedded decompressor. It uses more bytes, but less characters – you can often shave off 10-20 characters with compression. The beta adds a toggle that lets you view the uncompressed code, and it will re-compress it if you toggle it again, which you can abuse to compress your own dweets by pasting them in the edit window of a dweet remix and toggling on compression :-)
I am a regular code golfer and even to me this is shocking – the density seems to be violating laws of kolmogorov complexity. Obviously the “amount of information” is not as great as it feels (“it’s a whole city!”), but the effect is remarkable.