Why we are building another Minecraft client
There are plenty of 1.8.9 clients. None of them are ones you can read, change, or get cosmetics from without paying.

There is no shortage of Minecraft clients. Lunar, Badlion, Dawn and LabyMod are all more mature than this one, support more versions, and ship more mods. If you want the most polished 1.8.9 experience available today, one of those is probably still the right answer.
So why build another one?
Because you cannot read the others
Every large client is a closed binary. You install it, you grant it access to your account, and you trust that it does what it says. Most of the time that trust is well placed. But you cannot verify it, and you cannot change your mind about any part of it.
Matcha is the same kind of software with the opposite posture. The client, the matching server, the presence backend, the build tooling and the installer are all in one public repository. If you want to know what the client sends over the network, read the code that sends it. If you do not like how the keystroke overlay looks, change the twenty lines that draw it.
Because cosmetics should not cost money
Cosmetics are how players express themselves, and they have become the main way clients make money. That means the interesting capes are behind a payment, and the free ones are a sample.
We are not going to do that. Every cosmetic in Matcha is free, made by whoever wants to make one, reviewed in public, and credited to its author in the client. There is no store to build and no ranks to sell.
This is also the honest reason it is worth being open: a project with no revenue has nothing to protect by staying closed.
What it is today
Sixteen mods — the HUD elements, keystrokes, armour and potion status, toggle sprint, freelook, old animations, and a few quality-of-life additions. A HUD editor that snaps. A settings menu built from the mods’ own declarations, so a new setting appears in the UI as soon as it exists in the code. An installer that adds a profile to the launcher you already use, and does not touch anything else.
What it is not
It is new. It supports one Minecraft version. There is no support team, there are no cosmetics yet beyond samples, and you will find rough edges. If you need a client that already works perfectly for a hundred thousand people, this is not that.
If you want one you can help build, it is right here.