I found something that might be a bit too "shiny" for you. It has SOME dependencies, but does not pull the whole gnome|kde bloat with it, though. It works offline. Only the paid version has sync capabilities though.
EDIT: also found starcal2 which might work.
Get Rainlendar Lite (the Lite version is free):
http://www.rainlendar.net/cms/index.php?option=com_rny_download&Itemid=30
"Rainlendar is a customizable calendar application which stays out of your way but keeps all your important events and tasks always visible on your desktop."
Well, I tend to dip into both categories.
I'm not a programmer by profession (maybe one day!), I do a lot of development and projects on Linux purely for the ability to search through thousands of lines of code with powerful CLI tools like "grep".
On the other hand, I need the functionality and support that Ubuntu offers so that I can have apps like Rainlender, and Skype.
To give you a breakdown of my full set-up: I have Ubuntu on my desktop machine for day to day use.
I have Fedora 16 KDE on my Netbook, tweaked to have just a few lightweight IDEs for Java and C so I can do Arduino development and small scale projects on the go.
On my Thinkpad x220, I have Ubuntu. Mostly because the i7 is a dream for a laptop processor, and ease of communication between two Ubuntu systems is awesome.
Rainlendar or Rainmeter. Of the two, rainlendar is the simplest to-do list. It has a calendar, events, and a to-do list built in. You can get skins and make it match your theme.
Rainmeter is more complex but has higher potential. It can show you weather, RSS, hardware use, time, etc. But it's easy to get distratced customizing it and lose focus. Easier to make it look exactly how you want though.
http://www.rainlendar.net/cms/index.php
Runs in your system tray, you are in control on what's shown on your desktop (current year, current month, events, task reminder, or nothing at all), can be connected to a number of online calendars, and allows recurrent events in daily, weekly, monthly or even yearly intervals.
It's one of the very, very few pieces of software I actually shelled out money for.
I don't see any games mentioned. So I'll mention one. Because hey, Free games.
Urban Terror: http://www.urbanterror.info/
Basically it combines a lot from more popular 'Squad Based FPSes' like Counter Strike into a free game based on the Quake 3 Engine. Runs on a Potato if it needs to! Fun and Completely Free.
For actual Software:
Rainlendar 2 - http://www.rainlendar.net/cms/index.php
I use it for scheduling my everything and it sits on my desktop and is unobtrusive.
PC or phone?
If you're after a PC version, Rainlendar has a "to do" list feature which always shows your tasks even if you set them to 100% completion.
I just use Rainlendar, nothin special. It'd probably be more practical for me to use Google Calendar so that it'd sync with my phone. I started using Rainlendar way before I got a smartphone and just never bothered to switch.
I've been using Rainlendar for some time now. Should suit you're purposes quite nicely. Here is link to find some skins, I don't like the default ones very much.
Technology can motivate me, but not in the right way. Stupid flash games. If it's not Reddit that takes all my time it's Kongregate, or worse, stumble upon.
Anyway, the things that do help me are my little desktop apps Rainlendar and Keynote. Though I still prefer to use those good old todo notebooks I took from my work. Because there's nothing more satisfying than scratching out tasks and being able to doodle a bit (so it's obviously not my picture), that's something technology will never replace.
This keeps getting upvotes and no answer, so in the meantime I found something. Its called Rainlendar, and theres a second version out. Similar to rainmeter but different program