STALKER has amazing gameplay, but the graphics are kind of dated even compared to other games at the time of its release. Many consider the mod Complete 2009 as a must have if you want to give a boost in graphics to make it up-to-date. Besides, the atmospheric improvements like better/night cicles and spooky night sounds and better AI really adds to the experience.
I just recently tested Oblivion Lost mod, but it is very nice if you want more challenge and randomness, thus making the game more scary and unpredictable. Many consider that Complete 2009 mod is more suited for first time players as it preserves the playability intended by the developers and Oblivion Lost is for experienced players looking for new stuff and extra content.
Now, back to HoAE, it is very cool and entertaining mix of RTS/RPG, which is hard to find these days. There are some games like that I remember but I will mention only a handful of them.
Warcraft III: I remember playing WC3 and I love the way they incorporated elements of RPG in a RTS game. But I am not good at too much micromanagement of units and heroes at the same time, so I became attracted by the custom map for WC3 called Defense of the Ancients (DotA) as you have to control only one hero while other units are automatically built and commanded toward the enemy base. Then it came a game called League of Legends, which basically ports the explendid playability of DotA to a dedicated platform, and it's wonderful.
Rising Kingdoms: A very unknown game made by a bulgarian company, which is basically a WC3 but in 2D, which detracts people from even trying it as it is not graphically impressive. Besides, sound effects are very simple. If you can ignore these drawbacks, I found the playability quite interesting. You can choose 3 factions and each faction has 4 champions that play diferently from one another, the you collect glory points to learn skills, equip items and drink potions to increase your stats. The game plays much like WC3. If only it was released a couple years early maybe it could stand a chance compared with better known titles.
Celtic Kings - Rage of War: A 2D RTS featuring Romans vs. Gauls which allows armies of hundreds of units on screen at same time. You dont command units directly, but instead you control heroes and a hero control the army attached to his command. The hero gains levels and can benefit units under his command. Although the RPG aspects are not very emphazised, I found the playability very enjoyable if you like hundreds of units clashing together. Celtic Kings have 2 sequels called Punic Wars and Great Battles of Rome.
Dungeons & Dragons - Dragonshard: At first a RTS themed upon D&D seemed an awesome idea, but after playing Dragonshard I became very disappointed with the final product. First, your hero do not level up, which make him just like a regular unit, second your regular units level up but not through fighting, but simply by upgrading at the building they are trained. Third, the bases are very plain and boring. All doesn't mean the game is a total failure as it has many good aspects like collectable cristal shards falling from the sky, beautiful monster designs and animations and dark underground levels where you took a few soldiers to search for treasures just like a regular RPG. I just think this was not enough to stand firm compared to other better conceived games.
Kohan II - Kings of War: Sequel of a well praised RTS, but not the best example of mixed RTS/RPG game, but nonetheless a great underestimated title. This game is a solid fantasy themed RTS game, with less emphasis on base and resouces and more on tactics of combat. It sometimes resembles Battle for Middle Earth but the hero fights attached to a company of soldiers. The outcome of combat is decided by many factors like level, terrain, formation, flanking and even morale, as the more a company fights, it spends his morale bar until a break point when it run away fleeing and you temporarily lose control until it recovers some morale. A experience recommended more for RTS fans and less for RPG fans.
Well, I think I wrote too much, sorry for that, but I love RTS and RPG games. I played so many of then and it was hard for me to choose only a few examples. By the time I am writing this post I am very hooked on HoAE with it's unique feature of giving the player the option to play as a regular RTS, a classical RPG or a mix of both. I feel sorry for a game like this being so underrated. Sometimes I like to scavenge for not well known games and I found really nice forgotten jewels over these past years.