What were their complaints? Too difficult ( seems to be common feedback on the game, steep learning curve ).
I've heard of Roll20, but never played. Can you give us an upshot on what it's like? All I've ever played is D&D, Traveler and Top Secret ( and a few others for very short period of time like Gurps ). Top Secret has the greatest rule of any RPG ever ... so when you create your character, you pick one of 3 fields, for which Assassination is one of them ( the most popular selected, for obvious reasons ... there's Confiscation and Administration as well ). For the Assassination field, you get experience points no matter who you kill ... that means innocent civilians as well, bwaa ha ha ha haaa! Man, oh man, did I have fun playing that back in the day. I created my character and randomly went to the first house I came to in a random neighborhood, knocked on the door and started firing away with my shotgun, LOL! I never had so much fun! The cops typically took me out fairly quick, but just rolled up another one and kept going! It inspired me to think of a RPG where you're a serial killer ... but never did anything with it.
Anyhoo - let us know more about what you have in mind with Roll20, how you want to go about it, generally how it's played, etc.