Celeste

FNA

FNA is an open-source multi-platform reimplementation of the Microsoft XNA 4.0 libraries.

MonoGame

"MonoGame is an Open Source implementation of the Microsoft XNA 4 Framework. Our goal is to allow XNA developers on Xbox 360, Windows & Windows Phone to port their games to the iOS, Android, Mac OS X, Linux and Windows 8/10.As well as PlayStation Vita, Xbox One and PlayStation 4."

XNA Game Studio

XNA Game Studio 4.0 is a programming environment that allows you to use Visual Studio 2010 to create games for Windows Phone, the Xbox 360 console, and Windows-based computers. XNA Game Studio 4.0 includes the XNA Framework 4.0, which is a set of managed libraries designed for game development based on Microsoft .NET Framework 4.

Aseprite

Aseprite, formerly known as Allegro Sprite Editor, had its first release in 2001 as a free software project under the GPLv2 license. This license was kept until August 2016 with version v1.1.8, when the developers switched to a EULA, thus making the software proprietary. On the 1st of September 2016, the main developer, David Capello, wrote a post on the Aseprite Devblog explaining this change. The EULA permits others to download the Aseprite source code, compile it, and use it for personal purposes, but forbids its redistribution to third parties. After the license change, LibreSprite, a free and open source version of it was created. Both before and after the license change, Aseprite was sold online, on Steam, itch.io, and the project's website. The project's code repository was hosted on Google Code until August 2014, when it was migrated to GitHub, where it remains hosted to date. As of October 2022, its repository has had 68 contributors and around 19 thousand stars. From 2014 to 2021, Aseprite had 66 different releases, and has been used in the development of games such as TowerFall: Ascension, Celeste, Minit, Wargroove, Loop Hero, Eastward, Unpacking, Haiku the Robot and Pizza Tower.