Why did Marx's communist ideas appeal to most Russians?
Well, considering the situation of the Russians under the last Czar, we can imagine that any political idea involving change would have been welcome to a mass of people brutalized by the despotic monarchic government.
In reality Marx ideas were and are quite complex. Under Czar Nicholas II a huge number of Russians were basically illiterate, so the idea of, say, reading Das Kapital was a little bit peculiar.
The communists simply took some of these ideas to use and try to win the masses to their side and in doing so be able to gain control of the government.
Also, the majority of the Russians people under the Romanoff were maintained in a state of almost slavery with no rights, subjected, as objects of property, to the will of nobles and suffering periodically from famine, ill treatment and execution.
At the start the communist leaders such as Lenin "extracted" phrases and slogans from the work of Marx to attract the attention and support of the masses.
Slogans like: "the factories to the workers" or "the land to the farmers" were incredibly successful in a country where workers or farmers had nothing (no tools, no land, no profit from their work) and no hope for the future.
The main ideas I think, were:
1) Revolution against the nobles and "rich": particularly interesting for the population that in doing so could vindicate their sufferings and was tired to wait for reforms that never became real;
2) Distribution of wealth confiscated from the rich: obviously appealing to a population living in extreme poverty and constant danger of starvation;
3) Control of the government by the people: this was good in order to ensure that the old regime could never come back to oppress the masses again.
You could argue that religion as well had a similar message (love, fraternity, equality, respect, abundance and a prize for being good) but in religion you had to wait for the afterlife to get what you rightly deserved!
Marx gave us all of this and even more at the price of some “small” sacrifices.