A virtual machine designed by Andrew Plotkin which uses the Glk Application Programming Interface (API). The Inform language can be compiled for this virtual machine. Glulx imposes far less restrictive limitations on game size than the Z-machine and offers the I/O features of Glk, allowing Inform programmers to write larger games with more complicated user interfaces, without having to learn a new programming language.
- 3.1.0: Added support for block operations and heap memory allocation. Games using Inform 7's "indexed text" or "list" functionality require an interpreter that supports 3.1.0.
- 3.0.0: Added Unicode support.
- 2.0.0: Added modular I/O system system. The default I/O system is no longer Glk, which makes this an incompatible change.
- 1.0.0: Previous versions were all called "1.0.0"