There is a new game called gunrox
http://www.gunrox.com/?ref=Late That is very similar to ufo tactical part in gameplay. It is online multiplayer game, everyone has 3 soldiers and they can arm them as they want. When you gain levels you can allocate skillpoints and perks. Skillpoints make you better using a specific weapon group, damage and accuracy, and also allows you to use higher tier weapons. Perks can give you more health or more action points for example.
The game is free and you can play on a level field with players that do pay, but with cash you get some handy/nice options, like resetting skillpoints or perks, more item storage, customizable look of soldiers etc. You can also buy items with cash, but you can also loot items during games so if you are a decent player you dont really have to shop at all. Having said that, some builds require heavy shopping to work, for example you might be able to find one mine in one game average, so if you spec to mines you really need to shop them to effectively use them too.
You can also get veeery small amounts of ingame cash by reffing new people to the game, which is what I'm doing here but what I would really like is to make the game more known because the game is only fun if you have other people to play it with, and I'm getting so high level now its getting real hard :/ Anyway the game is awesome and you and your friends and mom should try it right away. Especially if you like jagged alliance or ufo or the like.