i can't echo JMS's suggestion enough. go with something simpler unless you plan on repeating senior year 3-4 times. even a single player 2d rpg is a lofty expectation unless you keep it really basic. ie, very basic dialogue/npc interaction (i'd keep it to a couple simple things like "quest giver" and "find the key" stuff), minimal object/inventory management (ie, 1 potion type, 1 "magic scroll", 1 weapon, 2 spells, etc etc. you get it). otherwise, you'd definitely be biting off more than you can chew. keep your goals for this very reasonable, allow some time to polish it up, and i think you could pull off something small but impressive in that amount of time.
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