Your problem areas?

[Wispy]

My continued learning experience has been off and on due to school, work and sometimes lack of direction. I’ve decided to make a little mystery game where using Spanish is a tool to advance in the story. I’m using this project to improve my Spanish and hopefully improve my programming skills.
I want the game to be 50% fun interactive novel and 50% learning experience. I don’t want to make a game where the premise is just an excuse to do grammar and vocabulary drills; (although these are important exercises) but I also want the user to take something useful away from the experience.
I decided to direct the game to people of an intermediate Spanish level and focus on areas that are a common source of trouble for students. Areas in which I have had trouble getting over the “bump” include: when to use preterite vs. imperfect, indirect object pronouns, and conjugating some verb tenses without wrinkling my forehead. I’d like to know the areas in which others had problems learning Spanish. Suggestions please?
-Wispy

[poli]

Both for Spanish speakers learning English and English speakers learning
Spanish prepositions are a big trap.

For English speakers, the subjunctive is very difficult. I find that there are
very logical rules, because Spanish as an official language is very new, modern and logical, but with all the rules, just using the language and being exposed to the subjunctive it helps most.

[bobjenkins]

Definativamente las areas en las que tengo los problemas son escucharlo, y hablarlo. Si tuviera que escoger un punto gramático, yo escogería las preposiciones.