Luckily, this library is big and has three reading rooms at the back end, allowingwith a handful of activities.

Instead of back end, you can just say back or "the far end".

Instead of allowing, it's more natural to just say "with".

On one table there was a used Monopoly,. I picked it up and called five classmates to play.

You can't use a comma to connect two independent clauses. Use a full stop to separate them into two sentences instead.

The match began normally, w. We started with 1,500 Monopoly money (MM) each and purchased properties as soon as possible.

Same as above.

I had only played Monopoly a few times, but I did happen to buy strategic properties, infor which I could ask for rent (typically no more than 30 MM).

"In" sounds a bit weird since you aren't physically inside the properties. You could say for, because you are asking for rent for the properties.

Everybody was afraid of landing on his hotel, b. By that point, I'd lost some money and had to sell 3 properties of mine to secure a quantity of MM.

DisgracefulUnfortunately, I did happen to land in his hotel and had to pay the amount of 750 MM,. I was bordering on bankruptcy, but things took a turn when another classmate rolled the dice and got a two, landed on my hotel, and had to pay me 1000 MM.

The word disgracefully isn't used very often in English, it's more natural to say unfortunately or unluckily.

Bordering (on) bankruptcy instead of bordering bankruptcy.

He went bankrupt and had to mortgage all of his properties, and I "inherited" all his money.

Same mistake with the comma connecting two independent clauses (comma splice). Here, I corrected it by adding "and". You can fix this by adding any of the FANBOYS conjunctions (co-ordinating conjunctions) after the comma: for, and, nor, but, or, yet, so.

AboutReturning to the first classmate, I did manage to make him go bankrupt and finally win the game.

Yesterday, after finishing my German listening comprehension exam, I had to walk to the library and wait for onean hour.

wait one hours is also okay but it's more common to say "for an hour" for one.

Luckily, this library is big and has three reading rooms atin the back end, allowing a handful of activities.

On one table there was a used Monopoly, set (or, "board game), so I picked it up and called up five classmates to play.

The match began normally,; we started with 1,500 Monopoly money (MM) and purchased properties as soon as possible.

I had only played Monopoly a few times, but I did happen to buy strategic properties, in which I could ask forallowed me to demand rent (typically no more than 30 MM).

Everybody was afraid of landing on his hotel, and by that point, I'd lost some money and had to sell 3 properties of mine to secure a quantity ofsome more MM.

Nonetheless, I secured a hotel for myself too, just in case something happene as a safeguard.

Disgracefully,Unfortunately? To my shame?... I did happen to land ion his hotel and had to pay the amount of 750 MM,. I was bordering on bankruptcy, but things took a turn when another classmate rolled the dice and got a two, which made him/her landed on my hotel, and had to pay me 1000 MM.

He went bankrupt and had to mortgage all of his properties,. I "inherited" all his money.

AboutIn regards to the first classmate, I did manage to make him go bankrupt and fineventually wion the game.