An alternative is to let you choose between progressive and flat income tax. That would require only two sliders and is also more realistic.
I guess there could be too different policies, flat tax and a progressive income tax, although I don’t have anything to prevent you having both policies at once. hmmmm.
How about nationalised policies, transport, utilities and industry.
It would add a business quality to the game. Increase car tax so more people use the bus and have nationalised transport.
How about a checkbox that lets you switch between flat and progressive?