How to play on older versions

Speedrunning on older versions:

Download the version you want here :
1.06.J787 (https://mega.nz/file/Xfwi3YaT#xpVj4t5nmgg4Sx2FlpOCXLDt3pvCfAKdZbHlmkvCNCA)
1.06.J791 (https://mega.nz/file/iOoyAITJ#qgqbHw4jErm4QHa1POtKdhPjZa3YJ_nEZQu3XIrgSPc)
1.06.J796 (https://mega.nz/file/TbpymaoA#3tn_0AkpsWrhKTvLvHIdBlC01PpEbI7mkFxJnAUWmDc)
1.06.J813 (https://mega.nz/file/qORiWbKa#_yiw7-xeXWXD8xEyklA62WxOxhw1JziyWyMHIretg_c)
1.06.J820 (https://mega.nz/file/TXomFIhR#q4SgZZU_DL4n4d6SmL1IuitptD2fBP-FE_myK60nHWY)
1.7.5 (https://mega.nz/file/nLgWnQyR#fjmdzIGPcFWn6ZCQ_ba0XbKEnSkbaDMMEqYvOLeTDpY)
1.7.6 (https://mega.nz/file/KHhgwaxD#t64Ixqb6NOj24QshsLbj95ARRFYcgNwtuk7p3Bc9c_U)
1.7.7a (https://mega.nz/file/regTxKrQ#O8U7MxRiVa8IESJM_JBOG5XUHzXnJeIE6khvc7u2SZg)
1.7.8a (https://mega.nz/file/3TwRRJoB#5wuVSofPaWvvp1Be7KA77yirtWPgm_qudQ1MORcmmww)
1.7.9a (https://mega.nz/file/TWAH1ZSD#WVxei3FOfe07rs-ckXZlPJVBFfYpep2YHd03f4pP6xY)
1.7.9b (https://mega.nz/file/CPJxkaZI#kIq7L2Qwu3u8ccYFxsviVfJRpCwDUnf28aZqiP9LB30)

And paste the files where your isaac is installed

To play again on the most recent version, download the latest version or uninstall/reinstall the game.