If you're looking for a minimal and simple calendar app then PinkCal might be for you.
Double tap a date to enter a new item. Single tap a date to view items starting at that date. Your selected date is shown in green. Items are listed under the calendar. Check out the screenshots.
Use the "early bird" setting, specified in minutes, to have reminders appear early.
For privacy reasons your data stays on your device and is never uploaded.