Before Mass Effect, there's Deus Ex. This second installment is quite as cool as the original.
There are tons of hidden corners and compartments for you to discover, making exploration a joy. And in this case, it's especially rewarding to be able to find rare items like biomod canisters or unique weapons that are strewn about the world of Deus Ex.
However, what bothers me is the trade system. You only get to buy stuff from dodgy traders, who sell limited items, and these items are often in abundance for you to find, except the biomod canisters. Moreover, you can't sell anything, which sort of makes trading in Deus Ex a redundant feature.
In normal mode, most of the combat encounters are laughable, but towards endgame where you uncover more "plots", enemies suddenly appear in a ridiculous lot in every corner. That's where your choice of bio-modification matters as they dictate the ease of your executions or escape. In other words, it's fun.
KingLim