RPG Toolkit is described as 'The RPG Toolkit is a free, open source project delivering a simple, flexible and powerful tool for the creation of role-playing games on your personal computer' and is an app in the Development category. There are more than 50 alternatives to RPG Toolkit for a variety of platforms, including Windows, Linux, Mac, Online / Web-based and Android. The best alternative is Godot Engine, which is both free and Open Source. Other great apps like RPG Toolkit are Unity (Free Personal), Unreal Engine (Freemium), GDevelop (Free, Open Source) and Wick Editor (Free, Open Source).
Godot is a fully featured, open source, MIT licensed game engine. It focuses on having great tools, and a visual oriented workflow that can export to PC, Mobile and Web platforms. It is a cross-platform 2D and 3D game engine and game development IDE.
Unreal Engine is a professional suite of tools and technologies used for building high-quality games across a range of platforms. Unreal Engine’s rendering architecture enables developers to achieve stunning visuals and also scale elegantly to lower-end systems.
GDevelop is an open-source game making software designed to be used by everyone. Any kind of 2D games can be created with it and no programming skills are required to get started. Logic of games are made using visual events.
The Wick Editor is a free and open-source tool for creating games, animations, and everything in-between. It's designed to be the most accessible tool for creating multimedia projects on the web. Your creations can run on any device with a web browser - that means mobile too.
Adventure Game Studio (AGS) - is the IDE and the engine meant for creating and running videogames of adventure (aka "quest") genre. It has potential, although limited, support for other genres as well.