28. Scorched Earth (Wendell Hicken, 1991)
At a glance, Scorched Earth isn't much to look at - a game with tiny sprites and simplistic VGA graphics where tanks shoot missiles and try to blow each other up. But then you take a closer look and find that this game is steeped in clever mechanics and surprisingly deep tactics. From MIRVs to Funky Bombs to Sandhogs, the game has a variety of interesting weapons to utilize, some of which can devastate everything on the screen (even their user) in short order. Further adding to the fun are defensive items like shields and options like having shots wrap around to the other side of the screen, bounce off the ceiling or radically shifting winds making aiming shots more difficult. In short, it's a game with a lot of options and endless replayability, especially in multi-player combat. The only real crime is that it never got an online play option!
I was never a big fan of shoot-em-up games; many of them start to feel very samey to me after a while, not to mention the fact that they feature one-hit deaths and swarming enemy patterns that are generally extremely trial-and-error based and require spot-on precision, and I don't really have the patience for that kind of thing. Tyrian 2000, however, is more my speed. An updated re-release of 1995's Tyrian, the game also features a lot of elements not normally seen in the genre - an in-depth storyline told between stages, a wide variety of customizable ship parts, weapons, sub-weapons and ship types, and even a pretty good sense of humor as you play through various minigames and collect giant fruits for points and have the option to pilot a ship that fires bananas and hot dogs at its enemies. Of course, the colorful graphics and sweet soundtrack also help, as does the fact that you actually have a health bar (in the form of a shield meter that regenerates over time and an armor meter that can only be restored via powerups). It still manages to be quite a challenge, but it's one that I can get into. Tyrian 2000 is a standout title and, for my money, the best top-down shmup ever made.
21. Starflight (Binary Systems, 1986)