Long time ago I made a tool for an online RTS game.
It could be run while watching a replay: It collected some data and afterwards it created some graphics and statistics.
(For example a heatmap where units were destroyed, how players had spent their resources, build orders)
Eventually, I made a bot that could sit in the lobby as a spectator and when the game was over then it created the statistics. It was several png images embedded in a html page that also contained some text.
I was quite a horrible construction of C++, Lua and delicate setup of external tools but it worked.
If I recall, I only knew how to save .bmp files but those were too big to upload. So the bot used irfanview to convert the images via commandline and then used an FTP program to upload.
It was funny to run the bot for a day and then read through the chatlog how players had reacted.
Sometimes they would try to talk to the bot. Sometimes there were long chats when the statistics showed that somebody had not helped the team, or people would point to something in the statistics that showed they had played well etc.
The various webhosters are long dead, only picture I can find right now is this:
Another time I played some multiplayer browser game, one of those games where you build up your empire and it ran for years. Basically the prototype of all those horrible mobile games, except it was entirely text or spreadsheet based.
With my tool you could copy lists of coordinates from the game and it would create maps, so you could see the borders between alliances etc. The maps were drawn with text symbols. There was also an option to output BB-Code with tons of color-tags and url-tags, so that you could copy-paste colored maps into message boards. The url-tag was used as tooltip, so it would show extra info in the browser status bar if you hovered the mouse on a point on the map.
There were also some other tools that would take too long to explain.
Anyway, the most exciting part for me was this: At first I only shared the tool to members of our alliance. But then someone actually cared enough to steal it!