I was wondering if the IPN simulator offered by PayPal Developer allows to use the option_selection values because I couldn't find it anywhere; I recall seeing it some time ago but it's suddenly gone. If there is no possibility at all to use it, is there an alternative to it I could use? Thanks.
There is not an option to pass over the option selection variables with the IPN simulator currently. You could either set up the IPN on your test sandbox account, and go through and make a test payment where you are passing these variables over otherwise you could create your own IPN testing tool. Similar to the following example.
<form target="_new" method="post" action="https://www.YourDomain.com/Path/IPNhandler.php">
<input type="hidden" name="SomePayPalVar" value="SomeValue1"/>
<input type="hidden" name="SomeOtherPPVar" value="SomeValue2"/>
Than etc for all other variables you want to test with.
</br>
<input type="submit"/>
</form>