Looks nice. The guys took a good look at trello, that's obvious. But I think they tackled some of the problems we're having with trello and some of the workflows we sortof patched on top of trello.
Yep, of course we got ideas from Trello! We love Trello, but it lacked some features which made it hard to use for us - Most importantly we were creating multiple boards on Trello to keep track of a single project (clients/remote teams/local teams/etc) and that's why we added in-project roles and permissions!
One thing that trello has on you is that I can make waaay more than 4 lists in trello. We usually have around 8-15 lists on a board.
You're not limited to 4 lists on Taskulu! You can have as many lists as you want (and Sheets/Boards within your projects). But To make it easier to follow the process, each list can have up to 4 sections (i.e. todo/doing/testing/done - You can change the section titles.) - if you change it so that each list has only one section it'll act exactly like Trello :)