Play as Isaac in Vampire Survivors. Isaac, his Tears and the Polyphemus evolution are loaded from your own copy of The Binding of Isaac: Rebirth while the game runs. Nothing from either game is shipped.
What you get
Isaac of the Basement, a new playable character at the end of the Character Selection list, with Isaac's own sprites and portrait. +10% damage every 10 levels (max +50%).
Tears, his starting weapon: Isaac's tears, fired in the direction he faces, with Isaac's tear sound. Levels 1-8 add tears, damage, speed and pierce.
Polyphemus: Tears at level 8 + max Spinach evolve from a chest into huge piercing tears with Isaac's Polyphemus icon.
Solo play.
Requirements
Vampire Survivors 1.16.107 or newer (Melty installs MelonLoader for you).
The Binding of Isaac: Rebirth installed on Steam. Without it, the game shows a notice and Isaac stays out.
Notes
The first start after installing takes a minute or two while MelonLoader prepares itself.
Includes a small plugin that fixes a MelonLoader 0.7.3 startup crash on Vampire Survivors 1.16 (Unity 6).
Credits
Isaac archive reader adapted from Gibbed.Rebirth by Rick (zlib License).